Metal-ligand complex catalyzed processes

ABSTRACT

This invention relates to a process which comprises reacting one or more reactants in the presence of a metal-organopolyphosphite ligand complex catalyst and optionally free organopolyphosphite ligand to produce a reaction product fluid comprising one or more products, wherein said process is conducted at a carbon monoxide partial pressure such that reaction rate increases as carbon monoxide partial pressure decreases and reaction rate decreases as carbon monoxide partial pressure increases and which is sufficient to prevent and/or lessen deactivation of the metal-organopolyphosphite ligand complex catalyst.

This application claims the benefit of provisional U.S. patentapplication Ser. Nos. 60/008,284, 60/008,286, 60/008,289 and 60/008,763,all filed Dec. 6, 1995, and all of which are incorporated herein byreference.

BRIEF SUMMARY OF THE INVENTION

1. Technical Field

This invention relates to an improved metal-organopolyphosphite ligandcomplex catalyzed hydroformylation process directed to producingaldehydes. More particularly, this invention relates to conducting thehydroformylation process in a reaction region where the hydroformylationreaction rate is of a negative or inverse order in carbon monoxide whichis sufficient to prevent and/or lessen deactivation of themetal-organopolyphosphite ligand complex catalyst and one or moreprocess parameters sufficient to prevent and/or lessen cycling of carbonmonoxide partial pressure, hydrogen partial pressure, hydroformylationreaction rate and/or temperature during said hydroformylation process.

2. Background of the Invention

It is well known in the art that aldehydes may be readily produced byreacting an olefinically unsaturated compound with carbon monoxide andhydrogen in the presence of a rhodium-organophosphite ligand complexcatalyst and that preferred processes involve continuoushydroformylation and recycling of the catalyst solution such asdisclosed, for example, in U.S. Pat. Nos. 4,148,830; 4,717,775 and4,769,498. Such aldehydes have a wide range of known utility and areuseful, for example, as intermediates for hydrogenation to aliphaticalcohols, for aldol condensation to produce plasticizers, for oxidationto produce aliphatic acids, etc.

However, notwithstanding the benefits attendant with suchrhodium-organophosphite ligand complex catalyzed hydroformylationprocesses, stabilization of the catalyst and organophosphite ligandremains a primary concern of the art. Obviously catalyst stability is akey issue in the employment of any catalyst. Loss of catalyst orcatalytic activity due to undesirable reactions of the highly expensiverhodium catalysts can be detrimental to the production of the desiredaldehyde. Likewise degradation of the organophosphite ligand employedduring the hydroformylation process can lead to poisoningorganophosphite compounds or inhibitors or acidic byproducts that canlower the catalytic activity of the rhodium catalyst. Moreover,production costs of the aldehyde product obviously increase whenproductivity of the catalyst decreases.

Numerous methods have been proposed to maintain catalyst and/ororganophosphite ligand stability. For instance, U.S. Pat. No. 5,288,918suggests employing a catalytic activity enhancing additive such as waterand/or a weakly acidic compound; U.S. Pat. No. 5,364,950 suggests addingan epoxide to stabilize the organophosphite ligand; and U.S. Pat. No.4,774,361 suggests carrying out the vaporization separation employed torecover the aldehyde product from the catalyst in the presence of anorganic polymer containing polar functional groups selected from theclass consisting of amide, ketone, carbamate, urea, and carbonateradicals in order to prevent and/or lessen rhodium precipitation fromsolution as rhodium metal or in the form of clusters of rhodium.Notwithstanding the value of the teachings of said references, thesearch for alternative methods and hopefully an even better and moreefficient means for stabilizing the rhodium catalyst and organophosphiteligand employed remains an ongoing activity in the art.

For instance, a major cause of organophosphite ligand degradation andcatalyst deactivation of rhodium-organophosphite ligand complexcatalyzed hydroformylation processes is due to the hydrolyticinstability of the organophosphite ligands. All organophosphites aresusceptible to hydrolysis in one degree or another, the rate ofhydrolysis of organophosphites in general being dependent on thestereochemical nature of the organophosphite. In general, the bulkierthe steric environment around the phosphorus atom, the slower thehydrolysis rate. For example, tertiary triorganophosphites such astriphenylphosphite are more susceptible to hydrolysis thandiorganophosphites, such as disclosed in U.S. Pat. No. 4,737,588, andorganopolyphosphites such as disclosed in U.S. Pat. Nos. 4,748,261 and4,769,498. Moreover, all such hydrolysis reactions invariably producephosphorus acidic compounds which catalyze the hydrolysis reactions. Forexample, the hydrolysis of a tertiary organophosphite produces aphosphonic acid diester, which is hydrolyzable to a phosphonic acidmonoester, which in turn is hydrolyzable to H₃ PO₃ acid. Moreover,hydrolysis of the ancillary products of side reactions, such as betweena phosphonic acid diester and the aldehyde or between certainorganophosphite ligands and an aldehyde, can lead to production ofundesirable strong aldehyde acids, e.g., n--C₃ H₇ CH(OH)P(O)(OH)₂.

Indeed even highly desirable sterically-hindered organobisphosphiteswhich are not very hydrolyzable can react with the aldehyde product toform poisoning organophosphites, e.g., organomonophosphites, which arenot only catalytic inhibitors, but far more susceptible to hydrolysisand the formation of such aldehyde acid byproducts, e.g., hydroxy alkylphosphonic acids, as shown, for example, in U.S. Pat. Nos. 5,288,918 and5,364,950. Further, the hydrolysis of organophosphite ligands may beconsidered as being autocatalytic in view of the production of suchphosphorus acidic compounds, e.g., H₃ PO₃, aldehyde acids such ashydroxy alkyl phosphonic acids, H₃ PO₄ and the like, and if leftunchecked the catalyst system of the continuous liquid recyclehydroformylation process will become more and more acidic in time. Thusin time the eventual build-up of an unacceptable amount of suchphosphorus acidic materials can cause the total destruction of theorganophosphite present, thereby rendering the hydroformylation catalysttotally ineffective (deactivated) and the valuable rhodium metalsusceptible to loss, e.g., due to precipitation and/or depositing on thewalls of the reactor.

Compounding the organophosphite stability problem is the need tocontinually hydrolyze a poisoning or inhibiting organomonophosphitereferred to above which forms during hydroformylation catalysis with ametal-organopolyphosphite ligand complex catalyst. For example, ifhydroformylation is operated under conventional conditions, a steadilydeclining catalyst activity is observed because of the accumulation ofinhibiting organomonophosphite/organopolyphosphite ligand-metalcomplexes. Attempts to prevent or lessen the accumulation of suchorganomonophosphite/organopolyphosphite ligand-metal complexes can causeundesirable disruption of hydroformylation operating parameters, e.g.,temperature, pressure, reaction rate, etc. Accordingly, a successfulmethod for preventing and/or lessening the accumulation of suchorganomonophosphite/organopolyphosphite ligand-metal complexes while atthe same time minimizing disruption of hydroformylation processparameters would be highly desirable to the art.

DISCLOSURE OF THE INVENTION

It has now been discovered that deactivation ofmetal-organopolyphosphite ligand complex catalysts caused by aninhibiting or poisoning organomonophosphite can be reversed or at leastminimized by carrying out hydroformylation processes in a reactionregion where the hydroformylation reaction rate is of a negative orinverse order in carbon monoxide and optionally at one or more of thefollowing conditions: at a temperature such that the temperaturedifference between reaction product fluid temperature and inlet coolanttemperature is sufficient to prevent and/or lessen cycling of carbonmonoxide partial pressure, hydrogen partial pressure, total reactionpressure, hydroformylation reaction rate and/or temperature during saidhydroformylation process; at a carbon monoxide conversion sufficient toprevent and/or lessen cycling of carbon monoxide partial pressure,hydrogen partial pressure, total reaction pressure, hydroformylationreaction rate and/or temperature during said hydroformylation process;at a hydrogen conversion sufficient to prevent and/or lessen cycling ofcarbon monoxide partial pressure, hydrogen partial pressure, totalreaction pressure, hydroformylation reaction rate and/or temperatureduring said hydroformylation process; and at an olefinic unsaturatedcompound conversion sufficient to prevent and/or lessen cycling ofcarbon monoxide partial pressure, hydrogen partial pressure, totalreaction pressure, hydroformylation reaction rate and/or temperatureduring said hydroformylation process.

This invention relates in part to a process which comprises reacting oneor more reactants in the presence of a metal-organopolyphosphite ligandcomplex catalyst and optionally free organopolyphosphite ligand toproduce a reaction product fluid comprising one or more products,wherein said process is conducted at a carbon monoxide partial pressuresuch that reaction rate increases as carbon monoxide partial pressuredecreases and reaction rate decreases as carbon monoxide partialpressure increases and which is sufficient to prevent and/or lessendeactivation of the metal-organopolyphosphite ligand complex catalyst.

This invention also relates in part to a hydroformylation process whichcomprises reacting one or more olefinic unsaturated compounds withcarbon monoxide and hydrogen in the presence of ametal-organopolyphosphite ligand complex catalyst and optionally freeorganopolyphosphite ligand to produce a reaction product fluidcomprising one or more aldehydes, wherein said hydroformylation processis conducted at a carbon monoxide partial pressure such thathydroformylation reaction rate increases as carbon monoxide partialpressure decreases and hydroformylation reaction rate decreases ascarbon monoxide partial pressure increases and which is sufficient toprevent and/or lessen deactivation of the metal-organopolyphosphiteligand complex catalyst and at one or more of the following conditions:(a) at a temperature such that the temperature difference betweenreaction product fluid temperature and inlet coolant temperature issufficient to prevent and/or lessen cycling of carbon monoxide partialpressure, hydrogen partial pressure, total reaction pressure,hydroformylation reaction rate and/or temperature during saidhydroformylation process, (b) at a carbon monoxide conversion sufficientto prevent and/or lessen cycling of carbon monoxide partial pressure,hydrogen partial pressure, total reaction pressure, hydroformylationreaction rate and/or temperature during said hydroformylation process,(c) at a hydrogen conversion sufficient to prevent and/or lessen cyclingof carbon monoxide partial pressure, hydrogen partial pressure, totalreaction pressure, hydroformylation reaction rate and/or temperatureduring said hydroformylation process, and (d) at an olefinic unsaturatedcompound conversion sufficient to prevent and/or lessen cycling ofcarbon monoxide partial pressure, hydrogen partial pressure, totalreaction pressure, hydroformylation reaction rate and/or temperatureduring said hydroformylation process.

This invention further relates in part to a hydroformylation processwhich comprises reacting one or more olefinic unsaturated compounds withcarbon monoxide and hydrogen in the presence of ametal-organopolyphosphite ligand complex catalyst and optionally freeorganopolyphosphite ligand to produce a reaction product fluidcomprising one or more aldehydes, wherein said hydroformylation processis conducted at a carbon monoxide partial pressure such thathydroformylation reaction rate increases as carbon monoxide partialpressure decreases and hydroformylation reaction rate decreases ascarbon monoxide partial pressure increases and which is sufficient toprevent and/or lessen deactivation of the metal-organopolyphosphiteligand complex catalyst, and at a temperature such that the temperaturedifference between reaction product fluid temperature and inlet coolanttemperature is sufficient to prevent and/or lessen cycling of carbonmonoxide partial pressure, hydrogen partial pressure, total reactionpressure, hydroformylation reaction rate and/or temperature during saidhydroformylation process, and at one or more of the followingconditions: (a) at a carbon monoxide conversion sufficient to preventand/or lessen cycling of carbon monoxide partial pressure, hydrogenpartial pressure, total reaction pressure, hydroformylation reactionrate and/or temperature during said hydroformylation process, (b) at ahydrogen conversion sufficient to prevent and/or lessen cycling ofcarbon monoxide partial pressure, hydrogen partial pressure, totalreaction pressure, hydroformylation reaction rate and/or temperatureduring said hydroformylation process, and (c) at an olefinic unsaturatedcompound conversion sufficient to prevent and/or lessen cycling ofcarbon monoxide partial pressure, hydrogen partial pressure, totalreaction pressure, hydroformylation reaction rate and/or temperatureduring said hydroformylation process.

This invention yet further relates in part to a hydroformylation processwhich comprises reacting one or more olefinic unsaturated compounds withcarbon monoxide and hydrogen in the presence of ametal-organopolyphosphite ligand complex catalyst and optionally freeorganopolyphosphite ligand to produce a reaction product fluidcomprising one or more aldehydes, wherein said hydroformylation processis conducted at a carbon monoxide partial pressure such thathydroformylation reaction rate increases as carbon monoxide partialpressure decreases and hydroformylation reaction rate decreases ascarbon monoxide partial pressure increases and which is sufficient toprevent and/or lessen deactivation of the metal-organopolyphosphiteligand complex catalyst, and at a carbon monoxide conversion sufficientto prevent and/or lessen cycling of carbon monoxide partial pressure,hydrogen partial pressure, total reaction pressure, hydroformylationreaction rate and/or temperature during said hydroformylation process.

This invention also relates in part to a hydroformylation process whichcomprises reacting one or more olefinic unsaturated compounds withcarbon monoxide and hydrogen in the presence of ametal-organopolyphosphite ligand complex catalyst and optionally freeorganopolyphosphite ligand to produce a reaction product fluidcomprising one or more aldehydes, wherein said hydroformylation processis conducted at a carbon monoxide partial pressure such thathydroformylation reaction rate increases as carbon monoxide partialpressure decreases and hydroformylation reaction rate decreases ascarbon monoxide partial pressure increases and which is sufficient toprevent and/or lessen deactivation of the metal-organopolyphosphiteligand complex catalyst, and at a hydrogen conversion sufficient toprevent and/or lessen cycling of carbon monoxide partial pressure,hydrogen partial pressure, total reaction pressure, hydroformylationreaction rate and/or temperature during said hydroformylation process.

This invention further relates in part to an improved hydroformylationprocess which comprises (i) reacting in at least one reaction zone oneor more olefinic unsaturated compounds with carbon monoxide and hydrogenin the presence of a metal-organopolyphosphite ligand complex catalystand optionally free organopolyphosphite ligand to produce a reactionproduct fluid comprising one or more aldehydes and (ii) separating in atleast one separation zone or in said at least one reaction zone the oneor more aldehydes from said reaction product fluid, the improvementcomprising preventing and/or lessening deactivation of themetal-organopolyphosphite ligand complex catalyst and preventing and/orlessening cycling of carbon monoxide partial pressure, hydrogen partialpressure, total reaction pressure, hydroformylation reaction rate and/ortemperature during said hydroformylation process by conducting saidhydroformylation process at a carbon monoxide partial pressure such thathydroformylation reaction rate increases as carbon monoxide partialpressure decreases and hydroformylation reaction rate decreases ascarbon monoxide partial pressure increases and at one or more of thefollowing conditions: (a) at a temperature such that the temperaturedifference between reaction product fluid temperature and inlet coolanttemperature is less than about 25° C., (b) at a carbon monoxideconversion of less than about 90%, (c) at a hydrogen conversion ofgreater than about 65%, and (d) at an olefinic unsaturated compoundconversion of greater than about 50%.

This invention yet further relates in part to a hydroformylation processwhich comprises reacting one or more olefinic unsaturated compounds withcarbon monoxide and hydrogen in the presence of ametal-organopolyphosphite ligand complex catalyst and optionally freeorganopolyphosphite ligand to produce a reaction product fluidcomprising one or more aldehydes, wherein said hydroformylation processis conducted at a carbon monoxide partial pressure such thathydroformylation reaction rate increases as carbon monoxide partialpressure decreases and hydroformylation reaction rate decreases ascarbon monoxide partial pressure increases and which is sufficient toprevent and/or lessen deactivation of the metal-organopolyphosphiteligand complex catalyst.

This invention also relates in part to an improved hydroformylationprocess which comprises (i) reacting in at least one reaction zone oneor more olefinic unsaturated compounds with carbon monoxide and hydrogenin the presence of a metal-organopolyphosphite ligand complex catalystand optionally free organopolyphosphite ligand to produce a reactionproduct fluid comprising one or more aldehydes and (ii) separating in atleast one separation zone or in said at least one reaction zone the oneor more aldehydes from said reaction product fluid, wherein saidreaction product fluid contains at least some organomonophosphite ligandformed during said hydroformylation process, the improvement comprisingconducting said hydroformylation process at a carbon monoxide partialpressure such that hydroformylation reaction rate increases as carbonmonoxide partial pressure decreases and hydroformylation reaction ratedecreases as carbon monoxide partial pressure increases and which issufficient to prevent and/or lessen coordination of theorganomonophosphite ligand with said metal-organopolyphosphite ligandcomplex catalyst and at one or more of the following conditions: (a) ata temperature such that the temperature difference between reactionproduct fluid temperature and inlet coolant temperature is sufficient toprevent and/or lessen cycling of carbon monoxide partial pressure,hydrogen partial pressure, total reaction pressure, hydroformylationreaction rate and/or temperature during said hydroformylation process,(b) at a carbon monoxide conversion sufficient to prevent and/or lessencycling of carbon monoxide partial pressure, hydrogen partial pressure,total reaction pressure, hydroformylation reaction rate and/ortemperature during said hydroformylation process, (c) at a hydrogenconversion sufficient to prevent and/or lessen cycling of carbonmonoxide partial pressure, hydrogen partial pressure, total reactionpressure, hydroformylation reaction rate and/or temperature during saidhydroformylation process, and (d) at an olefinic unsaturated compoundconversion sufficient to prevent and/or lessen cycling of carbonmonoxide partial pressure, hydrogen partial pressure, total reactionpressure, hydroformylation reaction rate and/or temperature during saidhydroformylation process.

This invention further relates in part to an improved hydroformylationprocess which comprises (i) reacting in at least one reaction zone oneor more olefinic unsaturated compounds with carbon monoxide and hydrogenin the presence of a metal-organopolyphosphite ligand complex catalystand optionally free organopolyphosphite ligand to produce a reactionproduct fluid comprising one or more aldehydes and (ii) separating in atleast one separation zone or in said at least one reaction zone the oneor more aldehydes from said reaction product fluid, wherein saidreaction product fluid contains at least some organomonophosphite ligandformed during said hydroformylation process, the improvement comprisingpreventing and/or lessening coordination of the organomonophosphiteligand with said metal-organopolyphosphite ligand complex catalyst andpreventing and/or lessening cycling of carbon monoxide partial pressure,hydrogen partial pressure, total reaction pressure, hydroformylationreaction rate and/or temperature during said hydroformylation process byconducting said hydroformylation process at a carbon monoxide partialpressure such that hydroformylation reaction rate increases as carbonmonoxide partial pressure decreases and hydroformylation reaction ratedecreases as carbon monoxide partial pressure increases and at one ormore of the following conditions: (a) at a temperature such that thetemperature difference between reaction product fluid temperature andinlet coolant temperature is less than about 25° C., (b) at a carbonmonoxide conversion of less than about 90%, (c) at a hydrogen conversionof greater than about 65%, and (d) at an olefinic unsaturated compoundconversion of greater than about 50%.

This invention yet further relates in part to a hydroformylation processwhich comprises reacting one or more olefinic unsaturated compounds withcarbon monoxide and hydrogen in the presence of ametal-organopolyphosphite ligand complex catalyst and optionally freeorganopolyphosphite ligand to produce a reaction product fluidcomprising one or more aldehydes, and in which said reaction productfluid contains at least some organomonophosphite ligand formed duringsaid hydroformylation process, wherein said hydroformylation process isconducted at a carbon monoxide partial pressure sufficient to preventand/or lessen coordination of the organomonophosphite ligand with saidmetal-organopolyphosphite ligand complex catalyst.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a graphical representation of the relationship betweenhydroformylation reaction rate and carbon monoxide partial pressure.

DETAILED DESCRIPTION

The hydroformylation processes of this invention may be asymmetric ornon-asymmetric, the preferred processes being non-asymmetric, and may beconducted in any continuous or semi-continuous fashion and may involveany catalyst liquid and/or gas recycle operation desired. Thus it shouldbe clear that the particular hydroformylation process for producing suchaldehydes from an olefinic unsaturated compound, as well as the reactionconditions and ingredients of the hydroformylation process are notcritical features of this invention. As used herein, the term"hydroformylation" is contemplated to include, but not limited to, allpermissible asymmetric and non-asymmetric hydroformylation processeswhich involve converting one or more substituted or unsubstitutedolefinic compounds or a reaction mixture comprising one or moresubstituted or unsubstituted olefinic compounds to one or moresubstituted or unsubstituted aldehydes or a reaction mixture comprisingone or more substituted or unsubstituted aldehydes. As used herein, theterm "reaction product fluid" is contemplated to include, but notlimited to, a reaction mixture containing an amount of any one or moreof the following: (a) a metal-organopolyphosphite ligand complexcatalyst, (b) free organopolyphosphite ligand, (c) one or morephosphorus acidic compounds formed in the reaction, (d) aldehyde productformed in the reaction, (e) unreacted reactants, and (f) an organicsolubilizing agent for said metal-organopolyphosphite ligand complexcatalyst and said free organopolyphosphite ligand. The reaction productfluid encompasses, but is not limited to, (a) the reaction medium in thereaction zone, (b) the reaction medium stream on its way to theseparation zone, (c) the reaction medium in the separation zone, (d) therecycle stream between the separation zone and the reaction zone, (e)the reaction medium withdrawn from the reaction zone or separation zonefor treatment in the acid removal zone, (f) the withdrawn reactionmedium treated in the acid removal zone, (g) the treated reaction mediumreturned to the reaction zone or separation zone, and (h) reactionmedium in external cooler.

Illustrative metal-organopolyphosphite ligand complex catalyzedhydroformylation processes which may experience such catalyticdeactivation include such processes as described, for example, in U.S.Pat. Nos. 4,148,830; 4,593,127; 4,769,498; 4,717,775; 4,774,361;4,885,401; 5,264,616; 5,288,918; 5,360,938; 5,364,950; and 5,491,266;the disclosures of which are incorporated herein by reference.Accordingly, the hydroformylation processing techniques of thisinvention may correspond to any known processing techniques. Preferredprocesses are those involving catalyst liquid recycle hydroformylationprocesses.

In general, such catalyst liquid recycle hydroformylation processesinvolve the production of aldehydes by reacting an olefinic unsaturatedcompound with carbon monoxide and hydrogen in the presence of ametal-organopolyphosphite ligand complex catalyst in a liquid mediumthat also contains an organic solvent for the catalyst and ligand.Preferably free organopolyphosphite ligand is also present in the liquidhydroformylation reaction medium. By "free organopolyphosphite ligand"is meant organopolyphosphite ligand that is not complexed with (tied toor bound to) the metal, e.g., metal atom, of the complex catalyst. Therecycle procedure generally involves withdrawing a portion of the liquidreaction medium containing the catalyst and aldehyde product from thehydroformylation reactor (i.e., reaction zone), either continuously orintermittently, and recovering the aldehyde product therefrom by use ofa composite membrane such as disclosed in U.S. Pat. No. 5,430,194 andcopending U.S. patent application Ser. No. 08/430,790, filed May 5,1995, the disclosures of which are incorporated herein by reference, orby the more conventional and preferred method of distilling it (i.e.,vaporization separation) in one or more stages under normal, reduced orelevated pressure, as appropriate, in a separate distillation zone, thenon-volatilized metal catalyst containing residue being recycled to thereaction zone as disclosed, for example, in U.S. Pat. No. 5,288,918.Condensation of the volatilized materials, and separation and furtherrecovery thereof, e.g., by further distillation, can be carried out inany conventional manner, the crude aldehyde product can be passed on forfurther purification and isomer separation, if desired, and anyrecovered reactants, e.g., olefinic starting material and syn gas, canbe recycled in any desired manner to the hydroformylation zone(reactor). The recovered metal catalyst containing raffinate of suchmembrane separation or recovered non-volatilized metal catalystcontaining residue of such vaporization separation can be recycled, tothe hydroformylation zone (reactor) in any conventional manner desired.

In a preferred embodiment, the hydroformylation reaction product fluidsemployable herein includes any fluid derived from any correspondinghydroformylation process that contains at least some amount of fourdifferent main ingredients or components, i.e., the aldehyde product, ametal-organopolyphosphite ligand complex catalyst, freeorganopolyphosphite ligand and an organic solubilizing agent for saidcatalyst and said free ligand, said ingredients corresponding to thoseemployed and/or produced by the hydroformylation process from whence thehydroformylation reaction mixture starting material may be derived. Itis to be understood that the hydroformylation reaction mixturecompositions employable herein can and normally will contain minoramounts of additional ingredients such as those which have either beendeliberately employed in the hydroformylation process or formed in situduring said process. Examples of such ingredients that can also bepresent include unreacted olefin starting material, carbon monoxide andhydrogen gases, and in situ formed type products, such as saturatedhydrocarbons and/or unreacted isomerized olefins corresponding to theolefin starting materials, and high boiling liquid aldehyde condensationbyproducts, as well as other inert co-solvent type materials orhydrocarbon additives, if employed.

Illustrative metal-organopolyphosphite ligand complex catalystsemployable in such hydroformylation reactions encompassed by thisinvention as well as methods for their preparation are well known in theart and include those disclosed in the above mentioned patents. Ingeneral such catalysts may be preformed or formed in situ as describedin such references and consist essentially of metal in complexcombination with an organopolyphosphite ligand. It is believed thatcarbon monoxide is also present and complexed with the metal in theactive species. The active species may also contain hydrogen directlybonded to the metal.

The catalyst useful in the hydroformylation process includes ametal-organopolyphosphite ligand complex catalyst which can be opticallyactive or non-optically active. The permissible metals which make up themetal-organopolyphosphite ligand complexes include Group 8, 9 and 10metals selected from rhodium (Rh), cobalt (Co), iridium (Ir), ruthenium(Ru), iron (Fe), nickel (Ni), palladium (Pd), platinum (Pt), osmium (Os)and mixtures thereof, with the preferred metals being rhodium, cobalt,iridium and ruthenium, more preferably rhodium, cobalt and ruthenium,especially rhodium. Other permissible metals include Group 6 metalsselected from chromium (Cr), molybdenum (Mo), tungsten (W) and mixturesthereof Mixtures of metals from Groups 6, 8, 9 and 10 may also be usedin this invention. The permissible organopolyphosphite ligands whichmake up the metal-organopolyphosphite ligand complexes and freeorganopolyphosphite ligand include mono-, di-, tri- and higherpolyorganophosphites. Mixtures of such ligands may be employed ifdesired in the metal-organopolyphosphite ligand complex catalyst and/orfree ligand and such mixtures may be the same or different. Thisinvention is not intended to be limited in any manner by the permissibleorganopolyphosphite ligands or mixtures thereof. It is to be noted thatthe successful practice of this invention does not depend and is notpredicated on the exact structure of the metal-organopolyphosphiteligand complex species, which may be present in their mononuclear,dinuclear and/or higher nuclearity forms. Indeed, the exact structure isnot known. Although it is not intended herein to be bound to any theoryor mechanistic discourse, it appears that the catalytic species may inits simplest form consist essentially of the metal in complexcombination with the organopolyphosphite ligand and carbon monoxideand/or hydrogen when used.

The term "complex" as used herein and in the claims means a coordinationcompound formed by the union of one or more electronically richmolecules or atoms capable of independent existence with one or moreelectronically poor molecules or atoms, each of which is also capable ofindependent existence. For example, the organopolyphosphite ligandsemployable herein may possess one or more phosphorus donor atoms, eachhaving one available or unshared pair of electrons which are eachcapable of forming a coordinate covalent bond independently or possiblyin concert (e.g., via chelation) with the metal. Carbon monoxide (whichis also properly classified as a ligand) can also be present andcomplexed with the metal. The ultimate composition of the complexcatalyst may also contain an additional ligand, e.g., hydrogen or ananion satisfying the coordination sites or nuclear charge of the metal.Illustrative additional ligands include, for example, halogen (Cl, Br,I), alkyl, aryl, substituted aryl, acyl, CF₃, C₂ F₅, CN, (R)₂ PO andRP(O)(OH)O (wherein each R is the same or different and is a substitutedor unsubstituted hydrocarbon radical, e.g., the alkyl or aryl), acetate,acetylacetonate, SO₄, PF₄, PF₆, NO₂, NO₃, CH₃ O, CH₂ ═CHCH₂, CH₃CH═CHCH₂, C₆ H₅ CN, CH₃ CN, NH₃, pyridine, (C₂ H₅)₃ N, mono-olefins,diolefins and triolefins, tetrahydrofuran, and the like. It is of courseto be understood that the complex species are preferably free of anyadditional organic ligand or anion that might poison the catalyst orhave an undue adverse effect on catalyst performance. It is preferred inthe metal-organopolyphosphite ligand complex catalyzed hydroformylationreactions that the active catalysts be free of halogen and sulfurdirectly bonded to the metal, although such may not be absolutelynecessary.

The number of available coordination sites on such metals is well knownin the art. Thus the catalytic species may comprise a complex catalystmixture, in their monomeric, dimeric or higher nuclearity forms, whichare preferably characterized by at least oneorganopolyphosphite-containing molecule complexed per one molecule ofmetal, e.g., rhodium. For instance, it is considered that the catalyticspecies of the preferred catalyst employed in a hydroformylationreaction may be complexed with carbon monoxide and hydrogen in additionto the organopolyphosphite ligands in view of the carbon monoxide andhydrogen gas employed by the hydroformylation reaction.

The organopolyphosphites that may serve as the ligand of themetal-organopolyphosphite ligand complex catalyst and/or free ligand ofthe hydroformylation processes and reaction product fluids of thisinvention may be of the achiral (optically inactive) or chiral(optically active) type and are well known in the art. Achiralorganopolyphosphites are preferred.

Among the organopolyphosphites that may serve as the ligand of themetal-organopolyphosphite ligand complex catalyst containing reactionproduct fluids of this invention and/or any free organopolyphosphiteligand of the hydroformylation process that might also be present insaid reaction product fluids are organopolyphosphite compounds describedbelow. Such organopolyphosphite ligands employable in this inventionand/or methods for their preparation are well known in the art.

Representative organopolyphosphites contain two or more tertiary(trivalent) phosphorus atoms and may include those having the formula:##STR1## wherein X represents a substituted or unsubstituted n-valentorganic bridging radical containing from 2 to 40 carbon atoms, each R¹is the same or different and represents a divalent organic radicalcontaining from 4 to 40 carbon atoms, each R² is the same or differentand represents a substituted or unsubstituted monovalent hydrocarbonradical containing from 1 to 24 carbon atoms, a and b can be the same ordifferent and each have a value of 0 to 6, with the proviso that the sumof a+b is 2 to 6 and n equals a+b. Of course it is to be understood thatwhen a has a value of 2 or more, each R¹ radical may be the same ordifferent, and when b has a value of 1 or more, each R² radical may bethe same or different.

Representative n-valent (preferably divalent) hydrocarbon bridgingradicals represented by X and representative divalent organic radicalsrepresented by R¹ above, include both acyclic radicals and aromaticradicals, such as alkylene, alkylene-Q_(m) -alkylene, cycloalkylene,arylene, bisarylene, arylene-alkylene, and arylene-(CH₂)_(y) --Q_(m)--(CH₂)_(y) -arylene radicals, and the like, wherein each y is the sameor different and is a value of 0 or 1, Q represents a divalent bridginggroup selected from --C(R³)₂ --, --O--, --S--, --NR⁴ --, Si(R⁵)₂ -- and--CO--, wherein each R³ is the same or different and representshydrogen, an alkyl radical having from 1 to 12 carbon atoms, phenyl,tolyl, and anisyl, R⁴ represents hydrogen or a substituted orunsubstituted monovalent hydrocarbon radical, e.g., an alkyl radicalhaving 1 to 4 carbon atoms; each R⁵ is the same or different andrepresents hydrogen or an alkyl radical, and m is a value of 0 or 1. Themore preferred acyclic radicals represented by X and R¹ above aredivalent alkylene radicals, while the more preferred aromatic radicalsrepresented by X and R¹ above are divalent arylene and bisaryleneradicals, such as disclosed more fully, for example, in U.S. Pat. Nos.4,769,498; 4,774,361: 4,885,401; 5,179,055; 5,113,022; 5,202,297;5,235,113; 5,264,616 and 5,364,950, and European Patent ApplicationPublication No. 662,468, and the like, the disclosures of which areincorporated herein by reference. Representative preferred monovalenthydrocarbon radicals represented by each R² radical above include alkyland aromatic radicals.

Illustrative preferred organopolyphosphites may include bisphosphitessuch as those of Formulas (II) to (IV) below: ##STR2## wherein each R¹,R² and X of Formulas (II) to (IV) are the same as defined above forFormula (I). Preferably each R¹ and X represents a divalent hydrocarbonradical selected from alkylene, arylene, arylene-alkylene-arylene, andbisarylene, while each R² radical represents a monovalent hydrocarbonradical selected from alkyl and aryl radicals. Organopolyphosphiteligands of such Formulas (II) to (IV) may be found disclosed, forexample, in U.S. Pat. Nos. 4,668,651; 4,748,261; 4,769,498; 4,774,361;4,885,401; 5,113,022; 5,179,055; 5,202,297; 5,235,113; 5,254,741;5,264,616; 5,312,996; 5,364,950; and 5,391,801; the disclosures of allof which are incorporated herein by reference.

Representative of more preferred classes of organobisphosphites arethose of the following Formulas (V) to (VII): ##STR3## wherein Q, R¹,R², X, m, and y are as defined above, and each Ar is the same ordifferent and represents a substituted or unsubstituted aryl radical.Most preferably X represents a divalent aryl-(CH₂)_(y) --(Q)_(m)--(CH₂)_(y) -aryl radical wherein each y individually has a value of 0or 1; m has a value of 0 or 1 and Q is --O--, --S-- or --C(R³)₂ whereeach R³ is the same or different and represents hydrogen or a methylradical. More preferably each alkyl radical of the above defined R²groups may contain from 1 to 24 carbon atoms and each aryl radical ofthe above-defined Ar, X, R¹ and R² groups of the above Formulas (V) to(VII) may contain from 6 to 18 carbon atoms and said radicals may be thesame or different, while the preferred alkylene radicals of X maycontain from 2 to 18 carbon atoms and the preferred alkylene radicals ofR¹ may contain from 5 to 18 carbon atoms. In addition, preferably thedivalent Ar radicals and divalent aryl radicals of X of the aboveformulas are phenylene radicals in which the bridging group representedby --CH₂)_(y) --(Q)_(m) --(CH₂)_(y) -- is bonded to said phenyleneradicals in positions that are ortho to the oxygen atoms of the formulasthat connect the phenylene radicals to their phosphorus atom of theformulae. It is also preferred that any substituent radical when presenton such phenylene radicals be bonded in the para and/or ortho positionof the phenylene radicals in relation to the oxygen atom that bonds thegiven substituted phenylene radical to its phosphorus atom.

Moreover, if desired any given organopolyphosphite in the above Formulas(I) to (VII) may be an ionic phosphite, i.e., may contain one or moreionic moieties selected from the group consisting of:

SO₃ M wherein M represents inorganic or organic cation,

PO₃ M wherein M represents inorganic or organic cation,

N(R⁶)₃ X¹ wherein each R⁶ is the same or different and represents ahydrocarbon radical containing from 1 to 30 carbon atoms, e.g., alkyl,aryl, alkaryl, aralkyl, and cycloalkyl radicals, and X¹ representsinorganic or organic anion,

CO₂ M wherein M represents inorganic or organic cation,

as described, for example, in U.S. Pat. Nos. 5,059,710; 5,113,0225,114,473; 5,449,653; and European Patent Application Publication No.435,084, the disclosures of which are incorporated herein by reference.Thus, if desired, such organopolyphosphite ligands may contain from 1 to3 such ionic moieties, while it is preferred that only one such ionicmoiety be substituted on any given aryl moiety in theorganopolyphosphite ligand when the ligand contains more than one suchionic moiety. As suitable counter-ions, M and X¹, for the anionicmoieties of the ionic organopolyphosphites there can be mentionedhydrogen (i.e. a proton), the cations of the alkali and alkaline earthmetals, e.g., lithium, sodium, potassium, cesium, rubidium, calcium,barium, magnesium and strontium, the ammonium cation and quaternaryammonium cations, phosphonium cations, arsonium cations and iminiumcations. Suitable anionic atoms of radicals include, for example,sulfate, carbonate, phosphate, chloride, acetate, oxalate and the like.

Of course any of the R¹, R², X, Q and Ar radicals of such non-ionic andionic organopolyphosphites of Formulas (I) to (VII) above may besubstituted if desired, with any suitable substituent containing from 1to 30 carbon atoms that does not unduly adversely affect the desiredresult of the process of this invention. Substituents that may be onsaid radicals in addition of course to corresponding hydrocarbonradicals such as alkyl, aryl, aralkyl, alkaryl and cyclohexylsubstituents, may include for example silyl radicals such as --Si(R⁷)₃ ;amino radicals such as --N(R⁷)₂ ; phosphine radicals such as-aryl-P(R⁷)₂ ; acyl radicals such as --C(O)R⁷ acyloxy radicals such as--OC(O)R⁷ ; amido radicals such as --CON(R⁷)₂ and --N(R⁷)COR⁷ ; sulfonylradicals such as --SO₂ R⁷, alkoxy radicals such as --OR⁷ ; sulfinylradicals such as --SOR⁷, sulfenyl radicals such as --SR⁷, phosphonylradicals such as --P(O)(R⁷)₂, as well as halogen, nitro, cyano,trifluoromethyl, hydroxy radicals, and the like, wherein each R⁷ radicalindividually represents the same or different monovalent hydrocarbonradical having from 1 to 18 carbon atoms (e.g., alkyl, aryl, aralkyl,alkaryl and cyclohexyl radicals), with the proviso that in aminosubstituents such as --N(R⁷)₂ each R⁷ taken together can also representa divalent bridging group that forms a heterocyclic radical with thenitrogen atom, and in amido substituents such as --C(O)N(R⁷)₂ and--N(R⁷)COR⁷ each R⁷ bonded to N can also be hydrogen. Of course it is tobe understood that any of the substituted or unsubstituted hydrocarbonradicals groups that make up a particular given organopolyphosphite maybe the same or different.

More specifically illustrative substituents include primary, secondaryand tertiary alkyl radicals such as methyl, ethyl, n-propyl, isopropyl,butyl, sec-butyl, t-butyl, neo-pentyl, n-hexyl, amyl, sec-amyl, t-amyl,iso-octyl, decyl, octadecyl, and the like; aryl radicals such as phenyl,naphthyl and the like; aralkyl radicals such as benzyl, phenylethyl,triphenylmethyl, and the like; alkaryl radicals such as tolyl, xylyl,and the like; alicyclic radicals such as cyclopentyl, cyclohexyl,1-methylcyclohexyl, cyclooctyl, cyclohexylethyl, and the like; alkoxyradicals such as methoxy, ethoxy, propoxy, t-butoxy, --OCH₂ CH₂ OCH₃,--O(CH₂ CH₂)₂ OCH₃, --O(CH₂ CH₂)₃ OCH₃, and the like; aryloxy radicalssuch as phenoxy and the like; as well as silyl radicals such as--Si(CH₃)₃, --Si(OCH₃)₃, --Si(C₃ H₇)₃, and the like; amino radicals suchas --NH₂, --N(CH₃)₂, --NHCH₃, --NH(C₂ H₅), and the like; arylphosphineradicals such as --P(C₆ H₅)₂, and the like; acyl radicals such as--C(O)CH₃, --C(O)C₂ H₅, --C(O)C₆ H₅, and the like; carbonyloxy radicalssuch as --C(O)OCH₃ and the like; oxycarbonyl radicals such as --O(CO)C₆H₅, and the like; amido radicals such as --CONH₂, --CON(CH₃)₂,--NHC(O)CH₃, and the like; sulfonyl radicals such as --S(O)₂ C₂ H₅ andthe like; sulfinyl radicals such as --S(O)CH₃ and the like; sulfenylradicals such as --SCH₃, --SC₂ H₅, --SC₆ H₅, and the like; phosphonylradicals such as --P(O)(C₆ H₅)₂, --P(O)(CH₃)₂, --P(O)(C₂ H₅)₂, --P(O)(C₃H₇)₂, --P(O)(C₄ H₉)₂, --P(O)(C₆ H₁₃)₂, --P(O)CH₃ (C₆ H₅), --P(O)(H)(C₆H₅), and the like.

Specific illustrative examples of such organobisphosphite ligandsinclude the following; ##STR4##

As noted above, the metal-organopolyphosphite ligand complex catalystsemployable in this invention may be formed by methods known in the art.The metal-organopolyphosphite ligand complex catalysts may be inhomogeneous or heterogeneous form. For instance, preformed rhodiumhydrido-carbonyl-organopolyphosphite ligand catalysts may be preparedand introduced into the reaction mixture of a hydroformylation process.More preferably, the rhodium-organopolyphosphite ligand complexcatalysts can be derived from a rhodium catalyst precursor which may beintroduced into the reaction medium for in situ formation of the activecatalyst. For example, rhodium catalyst precursors such as rhodiumdicarbonyl acetylacetonate, Rh₂ O₃, Rh₄ (CO)₁₂, Rh₆ (CO)₁₆, Rh(NO₃)₃ andthe like may be introduced into the reaction mixture along with theorganopolyphosphite ligand for the in situ formation of the activecatalyst. In a preferred embodiment of this invention, rhodiumdicarbonyl acetylacetonate is employed as a rhodium precursor andreacted in the presence of a solvent with the organopolyphosphite ligandto form a catalytic rhodium-organopolyphosphite ligand complex precursorwhich is introduced into the reactor along with excess (free)organopolyphosphite ligand for the in situ formation of the activecatalyst. In any event, it is sufficient for the purpose of thisinvention that carbon monoxide, hydrogen and organopolyphosphitecompound are all ligands that are capable of being complexed with themetal and that an active metal-organopolyphosphite ligand catalyst ispresent in the reaction mixture under the conditions used in thehydroformylation reaction.

More particularly, a catalyst precursor composition can be formedconsisting essentially of a solubilized metal-organopolyphosphite ligandcomplex precursor catalyst, an organic solvent and freeorganopolyphosphite ligand. Such precursor compositions may be preparedby forming a solution of a rhodium starting material, such as a rhodiumoxide, hydride, carbonyl or salt, e.g. a nitrate, which may or may notbe in complex combination with a organopolyphosphite ligand as definedherein. Any suitable rhodium starting material may be employed, e.g.rhodium dicarbonyl acetylacetonate, Rh₂ O₃, Rh₄ (CO)₁₂, Rh₆ (CO)₁₆,Rh(NO₃)₃, and organopolyphosphite ligand rhodium carbonyl hydrides.Carbonyl and organopolyphosphite ligands, if not already complexed withthe initial rhodium, may be complexed to the rhodium either prior to orin situ during the hydroformylation process.

By way of illustration, the preferred catalyst precursor composition ofthis invention consists essentially of a solubilized rhodium carbonylorganopolyphosphite ligand complex precursor catalyst, a solvent andoptionally free organopolyphosphite ligand prepared by forming asolution of rhodium dicarbonyl acetylacetonate, an organic solvent and aorganopolyphosphite ligand as defined herein. The organopolyphosphiteligand readily replaces one of the carbonyl ligands of the rhodiumacetylacetonate complex precursor at room temperature as witnessed bythe evolution of carbon monoxide gas. This substitution reaction may befacilitated by heating the solution if desired. Any suitable organicsolvent in which both the rhodium dicarbonyl acetylacetonate complexprecursor and rhodium organopolyphosphite ligand complex precursor aresoluble can be employed. The amounts of rhodium complex catalystprecursor, organic solvent and organopolyphosphite ligand, as well astheir preferred embodiments present in such catalyst precursorcompositions may obviously correspond to those amounts employable in thehydroformylation process of this invention. Experience has shown thatthe acetylacetonate ligand of the precursor catalyst is replaced afterthe hydroformylation process has begun with a different ligand, e.g.,hydrogen, carbon monoxide or organopolyphosphite ligand, to form theactive complex catalyst as explained above. The acetylacetone which isfreed from the precursor catalyst under hydroformylation conditions isremoved from the reaction medium with the product aldehyde and thus isin no way detrimental to the hydroformylation process. The use of suchpreferred rhodium complex catalytic precursor compositions provides asimple economical and efficient method for handling the rhodiumprecursor and hydroformylation start-up.

Accordingly, the metal-organopolyphosphite ligand complex catalysts usedin the process of this invention consists essentially of the metalcomplexed with carbon monoxide and a organopolyphosphite ligand, saidligand being bonded (complexed) to the metal in a chelated and/ornon-chelated fashion. Moreover, the terminology "consists essentiallyof", as used herein, does not exclude, but rather includes, hydrogencomplexed with the metal, in addition to carbon monoxide and theorganopolyphosphite ligand. Further, such terminology does not excludethe possibility of other organic ligands and/or anions that might alsobe complexed with the metal. Materials in amounts which unduly adverselypoison or unduly deactivate the catalyst are not desirable and so thecatalyst most desirably is free of contaminants such as metal-boundhalogen (e.g., chlorine, and the like) although such may not beabsolutely necessary. The hydrogen and/or carbonyl ligands of an activemetal-organopolyphosphite ligand complex catalyst may be present as aresult of being ligands bound to a precursor catalyst and/or as a resultof in situ formation, e.g., due to the hydrogen and carbon monoxidegases employed in hydroformylation process of this invention.

As noted the hydroformylation processes of this invention involve theuse of a metal-organopolyphosphite ligand complex catalyst as describedherein. Of course mixtures of such catalysts can also be employed ifdesired. The amount of metal-organopolyphosphite ligand complex catalystpresent in the reaction medium of a given hydroformylation processencompassed by this invention need only be that minimum amount necessaryto provide the given metal concentration desired to be employed andwhich will furnish the basis for at least the catalytic amount of metalnecessary to catalyze the particular hydroformylation process involvedsuch as disclosed, for example, in the above-mentioned patents. Ingeneral, metal, e.g., rhodium, concentrations in the range of from about10 parts per million to about 1000 parts per million, calculated as freerhodium, in the hydroformylation reaction medium should be sufficientfor most processes, while it is generally preferred to employ from about10 to 500 parts per million of metal, e.g., rhodium, and more preferablyfrom 25 to 350 parts per million of metal, e.g., rhodium.

In addition to the metal-organopolyphosphite ligand complex catalyst,free organopolyphosphite ligand (i.e., ligand that is not complexed withthe metal) may also be present in the hydroformylation reaction medium.The free organopolyphosphite ligand may correspond to any of theabove-defined organopolyphosphite ligands discussed above as employableherein. It is preferred that the free organopolyphosphite ligand be thesame as the organopolyphosphite ligand of the metal-organopolyphosphiteligand complex catalyst employed. However, such ligands need not be thesame in any given process. The hydroformylation process of thisinvention may involve from about 0.1 moles or less to about 100 moles orhigher, of free organopolyphosphite ligand per mole of metal in thehydroformylation reaction medium. Preferably the hydroformylationprocess of this invention is carried out in the presence of from about 1to about 50 moles of organopolyphosphite ligand, and more preferably fororganopolyphosphites from about 1.1 to about 4 moles oforganopolyphosphite ligand, per mole of metal present in the reactionmedium; said amounts of organopolyphosphite ligand being the sum of boththe amount of organopolyphosphite ligand that is bound (complexed) tothe metal present and the amount of free (non-complexed)organopolyphosphite ligand present. Since it is more preferred toproduce non-optically active aldehydes by hydroformylating achiralolefins, the more preferred organopolyphosphite ligands are achiral typeorganopolyphosphite ligands, especially those encompassed by Formula (I)above, and more preferably those of Formulas (II) and (V) above. Ofcourse, if desired, make-up or additional organopolyphosphite ligand canbe supplied to the reaction medium of the hydroformylation process atany time and in any suitable manner, e.g. to maintain a predeterminedlevel of free ligand in the reaction medium.

As indicated above, the hydroformylation catalyst may be inheterogeneous form during the reaction and/or during the productseparation. Such catalysts are particularly advantageous in thehydroformylation of olefins to produce high boiling or thermallysensitive aldehydes, so that the catalyst may be separated from theproducts by filtration or decantation at low temperatures. For example,the rhodium catalyst may be attached to a support so that the catalystretains its solid form during both the hydroformylation and separationstages, or is soluble in a liquid reaction medium at high temperaturesand then is precipitated on cooling.

As an illustration, the rhodium catalyst may be impregnated onto anysolid support, such as inorganic oxides, (i.e. alumina, silica, titania,or zirconia) carbon, or ion exchange resins. The catalyst may besupported on, or intercalated inside the pores of, a zeolite, glass orclay; the catalyst may also be dissolved in a liquid film coating thepores of said zeolite or glass. Such zeolite-supported catalysts areparticularly advantageous for producing one or more regioisomericaldehydes in high selectivity, as determined by the pore size of thezeolite. The techniques for supporting catalysts on solids, such asincipient wetness, which will be known to those skilled in the art. Thesolid catalyst thus formed may still be complexed with one or more ofthe ligands defined above. Descriptions of such solid catalysts may befound in for example: J. Mol. Cat. 1991, 70, 363-368; Catal. Lett. 1991,8, 209-214; J. Organomet. Chem, 1991, 403, 221-227; Nature, 1989, 339,454-455; J. Catal. 1985, 96, 563-573; J. Mol. Cat. 1987, 39, 243-259.

The metal, e.g., rhodium, catalyst may be attached to a thin film ormembrane support, such as cellulose acetate or polyphenylenesulfone, asdescribed in for example J. Mol. Cat. 1990, 63, 213-221.

The metal, e.g., rhodium, catalyst may be attached to an insolublepolymeric support through an organophosphorus-containing ligand, such asa phosphite, incorporated into the polymer. The supported catalyst isnot limited by the choice of polymer or phosphorus-containing speciesincorporated into it. Descriptions of polymer-supported catalysts may befound in for example: J. Mol. Cat. 1993, 83, 17-35; Chemtech 1983, 46;J. Am. Chem. Soc. 1987, 109, 7122-7127.

In the heterogeneous catalysts described above, the catalyst may remainin its heterogeneous form during the entire hydroformylation andcatalyst separation process. In another embodiment of the invention, thecatalyst may be supported on a polymer which, by the nature of itsmolecular weight, is soluble in the reaction medium at elevatedtemperatures, but precipitates upon cooling, thus facilitating catalystseparation from the reaction mixture. Such "soluble" polymer-supportedcatalysts are described in for example: Polymer, 1992, 33, 161; J. Org.Chem. 1989, 54, 2726-2730.

More preferably, the reaction is carried out in the slurry phase due tothe high boiling points of the products, and to avoid decomposition ofthe product aldehydes. The catalyst may then be separated from theproduct mixture, for example, by filtration or decantation. The reactionproduct fluid may contain a heterogeneous metal-organopolyphosphiteligand complex catalyst, e.g., slurry, or at least a portion of thereaction product fluid may contact a fixed heterogeneousmetal-organopolyphosphite ligand complex catalyst during thehydroformylation process. In an embodiment of this invention, themetal-organopolyphosphite ligand complex catalyst may be slurried in thereaction product fluid.

The substituted or unsubstituted olefinic unsaturated starting materialreactants that may be employed in the hydroformylation processes of thisinvention include both optically active (prochiral and chiral) andnon-optically active (achiral) olefinic unsaturated compounds containingfrom 2 to 40, preferably 4 to 20, carbon atoms. Such olefinicunsaturated compounds can be terminally or internally unsaturated and beof straight-chain, branched chain or cyclic structures, as well asolefin mixtures, such as obtained from the oligomerization of propene,butene, isobutene, etc. (such as so called dimeric, trimeric ortetrameric propylene and the like, as disclosed, for example, in U.S.Pat. Nos. 4,518,809 and 4,528,403). Moreover, such olefin compounds mayfurther contain one or more ethylenic unsaturated groups, and of course,mixtures of two or more different olefinic unsaturated compounds may beemployed as the starting hydroformylation material if desired. Forexample, commercial alpha olefins containing four or more carbon atomsmay contain minor amounts of corresponding internal olefins and/or theircorresponding saturated hydrocarbon and that such commercial olefinsneed not necessarily be purified from same prior to beinghydroformylated. Illustrative mixtures of olefinic starting materialsthat can be employed in the hydroformylation reactions include, forexample, mixed butenes, e.g., Raffinate I and II. Further such olefinicunsaturated compounds and the corresponding aldehyde products derivedtherefrom may also contain one or more groups or substituents which donot unduly adversely affect the hydroformylation process or the processof this invention such as described, for example, in U.S. Pat. Nos.3,527,809, 4,769,498 and the like.

Most preferably the subject invention is especially useful for theproduction of non-optically active aldehydes, by hydroformylatingachiral alpha-olefins containing from 2 to 30, preferably 4 to 20,carbon atoms, and achiral internal olefins containing from 4 to 20carbon atoms as well as starting material mixtures of such alpha olefinsand internal olefins.

Illustrative alpha and internal olefins include, for example, ethylene,propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-nonene, 1-decene,1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene,1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene,2-butene, 2-methyl propene (isobutylene), 2-methylbutene, 2-pentene,2-hexene, 3-hexane, 2-heptene, 2-octene, cyclohexene, propylene dimers,propylene trimers, propylene tetramers, butadiene, piperylene, isoprene,2-ethyl-1-hexene, styrene, 4-methyl styrene, 4-isopropyl styrene,4-tert-butyl styrene, alpha-methyl styrene, 4-tert-butyl-alpha-methylstyrene, 1,3-diisopropenylbenzene, 3-phenyl-1-propene, 1,4-hexadiene,1,7-octadiene, 3-cyclohexyl-1-butene, and the like, as well as,1,3-dienes, butadiene, alkyl alkenoates, e.g., methyl pentenoate,alkenyl alkanoates, alkenyl alkyl ethers, alkenols, e.g., pentenols,alkenals, e.g., pentenals, and the like, such as allyl alcohol, allylbutyrate, hex-1-en-4-ol, oct-1-en-4-ol, vinyl acetate, allyl acetate,3-butenyl acetate, vinyl propionate, allyl propionate, methylmethacrylate, vinyl ethyl ether, vinyl methyl ether, allyl ethyl ether,n-propyl-7-octenoate, 3-butenenitrile, 5-hexenamide, eugenol,iso-eugenol, safrole, iso-safrole, anethol, 4-allylanisole, indene,limonene, beta-pinene, dicyclopentadiene, cyclooctadiene, camphene,linalool, and the like.

Prochiral and chiral olefins useful in the asymmetric hydroformylationthat can be employed to produce enantiomeric aldehyde mixtures that maybe encompassed by in this invention include those represented by theformula: ##STR5## wherein R₁, R₂, R₃ and R₄ are the same or different(provided R₁ is different from R₂ or R₃ is different from R₄) and areselected from hydrogen; alkyl; substituted alkyl, said substitutionbeing selected from dialkylamino such as benzylamino and dibenzylamino,alkoxy such as methoxy and ethoxy, acyloxy such as acetoxy, halo, nitro,nitrile, thio, carbonyl, carboxamide, carboxaldehyde, carboxyl,carboxylic ester; aryl including phenyl; substituted aryl includingphenyl, said substitution being selected from alkyl, amino includingalkylamino and dialkylamino such as benzylamino and dibenzylamino,hydroxy, alkoxy such as methoxy and ethoxy, acyloxy such as acetoxy,halo, nitrile, nitro, carboxyl, carboxaldehyde, carboxylic ester,carbonyl, and thio; acyloxy such as acetoxy; alkoxy such as methoxy andethoxy; amino including alkylamino and dialkylamino such as benzylaminoand dibenzylamino; acylamino and diacylamino such as acetylbenzylaminoand diacetylamino; nitro; carbonyl; nitrile; carboxyl; carboxamide;carboxaldehyde; carboxylic ester; and alkylmercapto such asmethylmercapto. It is understood that the prochiral and chiral olefinsof this definition also include molecules of the above general formulawhere the R groups are connected to form ring compounds, e.g.,3-methyl-1-cyclohexene, and the like.

Illustrative optically active or prochiral olefinic compounds useful inasymmetric hydroformylation include, for example, p-isobutylstyrene,2-vinyl-6-methoxy-2-naphthylene, 3-ethenylphenyl phenyl ketone,4-ethenylphenyl-2-thienylketone, 4-ethenyl-2-fluorobiphenyl,4-(1,3-dihydro-1-oxo-2H-isoindol-2-yl)styrene,2-ethenyl-5-benzoylthiophene, 3-ethenylphenyl phenyl ether,propenylbenzene, isobutyl-4-propenylbenzene, phenyl vinyl ether and thelike. Other olefinic compounds include substituted aryl ethylenes asdescribed, for example, in U.S. Pat. Nos. 4,329,507, 5,360,938 and5,491,266, the disclosures of which are incorporated herein byreference.

Illustrative of suitable substituted and unsubstituted olefinic startingmaterials include those permissible substituted and unsubstitutedolefinic compounds described in Kirk-Othmer, Encyclopedia of ChemicalTechnology, Fourth Edition, 1996, the pertinent portions of which areincorporated herein by reference.

The reaction conditions of the hydroformylation processes encompassed bythis invention may include any suitable type hydroformylation conditionsheretofore employed for producing optically active and/or non-opticallyactive aldehydes. For instance, the total gas pressure of hydrogen,carbon monoxide and olefin starting compound of the hydroformylationprocess may range from about 1 to about 10,000 psia. In general,however, it is preferred that the process be operated at a total gaspressure of hydrogen, carbon monoxide and olefin starting compound ofless than about 2000 psia and more preferably less than about 500 psia.The minimum total pressure is limited predominately by the amount ofreactants necessary to obtain a desired rate of reaction. Morespecifically the carbon monoxide partial pressure of thehydroformylation process of this invention is preferable from about 1 toabout 1000 psia, and more preferably from about 3 to about 800 psia,while the hydrogen partial pressure is preferably about 5 to about 500psia and more preferably from about 10 to about 300 psia. In general H₂:CO molar ratio of gaseous hydrogen to carbon monoxide may range fromabout 1:10 to 100:1 or higher, the more preferred hydrogen to carbonmonoxide molar ratio being from about 1:10 to about 10:1. Further, thehydroformylation process may be conducted at a reaction temperature fromabout -25° C. to about 200° C. In general hydroformylation reactiontemperatures of about 50° C. to about 120° C. are preferred for alltypes of olefinic starting materials. Of course it is to be understoodthat when non-optically active aldehyde products are desired, achiraltype olefin starting materials and organopolyphosphite ligands areemployed and when optically active aldehyde products are desiredprochiral or chiral type olefin starting materials andorganopolyphosphite ligands are employed. Of course, it is to be alsounderstood that the hydroformylation reaction conditions employed willbe governed by the type of aldehyde product desired.

As stated above, the subject invention resides in the discovery thatdeactivation of such metal-organopolyphosphite ligand complex catalystscaused by an inhibiting or poisoning organomonophosphite can be reversedor at least minimized by carrying out the hydroformylation process in areaction region where the hydroformylation reaction rate is of anegative or inverse order in carbon monoxide and one or more of thefollowing: at a temperature such that the temperature difference betweenreaction product fluid temperature and inlet coolant temperature is lessthan about 25° C., preferably less than about 20° C., and morepreferably less than about 15° C.; at a carbon monoxide conversion ofless than about 90%, preferably less than about 75%, and more preferablyless than about 65%; at a hydrogen conversion of greater than about 65%,preferably greater than about 85%, and more preferably greater thanabout 90%; and/or at an olefinic unsaturated compound conversion ofgreater than about 50%, preferably greater than about 60%, and morepreferably greater than about 70%. When the hydroformylation reactionrate is of a negative or inverse order in carbon monoxide, the carbonmonoxide partial pressure is sufficiently high that the inhibiting orpoisoning organomonophosphite byproduct does not coordinate with and/ordissociates from the metal-organopolyphosphite ligand complex catalyst.At higher carbon monoxide partial pressures where the hydroformylationreaction rate has a negative order in carbon monoxide, carbon monoxidecoordinates more effectively with respect to the metal of themetal-organopolyphosphite ligand complex catalyst greater than theinhibiting organomonophosphite and competes with the inhibitingorganomonophosphite for the free coordination site on the metal, e.g.,rhodium, thereby increasing the concentration of inhibitingorganomonophosphite in solution. The inhibiting or poisoningorganomonophosphite in solution can then be hydrolyzed with water, aweakly acidic compound, or both added water and a weakly acidiccompound. See, for example, U.S. Pat. No. 5,288,918.

As used herein, a hydroformylation reaction rate that is of negative orinverse order in carbon monoxide refers to a hydroformylation reactionrate in which the carbon monoxide partial pressure is such that thehydroformylation reaction rate increases as carbon monoxide partialpressure decreases and the hydroformylation reaction rate decreases ascarbon monoxide partial pressure increases. See, for example, FIG. 1which graphically illustrates this negative or inverse relationshipbetween hydroformylation reaction rate and carbon monoxide partialpressure.

Without wishing to be bound to any exact theory or mechanisticdiscourse, it appears that the structural features of certainorganopolyphosphite ligands which make them such beneficially uniquehydroformylation catalysts as discussed, for example, in U.S. Pat. No.4,668,651, are also a cause of the intrinsic catalyst deactivationdiscussed herein. The activity of the metal-organopolyphosphite ligandcomplex catalyst declines as inhibiting catalyst concentration builds.

For instance while metal-organopolyphosphite ligand complex catalysts ofthe type employable herein have been found to be highly active andselective in hydroformylation processes in converting terminal as wellas internal olefins to aldehydes, it has also been observed that suchcatalyst systems undergo a loss in catalytic activity over time. In thecourse of studying such catalysts, the formation of a class ofdiorganophosphite byproducts have been discovered which can best bedescribed as organomonophosphite decomposition products of theorganopolyphosphite ligand employed. Such evidence is consistent withthe view that the organopolyphosphite reacts with an alcohol or analkoxy radical, such as likely to arise from the reaction of thealdehyde product and hydrogen (or hydride), to form an alkyl1,1'-biaryl-2,2'-diyl! phosphite, i.e. an organomonophosphite byproduct,which may be further identifiable and characterizable by conventionalanalytical techniques, such as Phosphorus-31 nuclear magnetic resonancespectroscopy and Fast Atom Bombardment Mass Spectroscopy. The intrinsiccatalyst deactivation of the preferred metal-organopolyphosphite ligandcomplex catalyst is thus believed to be primarily caused by suchorganomonophosphite byproduct which acts as a catalyst poison orinhibitor by competing for coordination sites on the metal and formingcomplexes that are far less catalytically reactive than the preferredmetal-organopolyphosphite ligand complex catalyst employed.

A means for reversing or greatly minimizing such intrinsic catalystdeactivation has now been discovered which comprises carrying out thehydroformylation process in a reaction region where the hydroformylationreaction rate is of a negative or inverse order in carbon monoxide andone or more of the following: at a temperature such that the temperaturedifference between reaction product fluid temperature and inlet coolanttemperature is less than about 25° C., preferably less than about 20°C., and more preferably less than about 15° C.; at a carbon monoxideconversion of less than about 90%, preferably less than about 75%, andmore preferably less than about 65%; at a hydrogen conversion of greaterthan about 65%, preferably greater than about 85%, and more preferablygreater than about 90;, and/or at an olefinic unsaturated compoundconversion of greater than about 50%, preferably greater than about 60%,and more preferably greater than about 70%.

It has now been discovered that the catalyst activity of ametal-organopolyphosphite ligand complex catalyst that has become atleast partially intrinsically deactivated due to the formation oforganomonophosphite ligand byproduct over continuous hydroformylation,can be restored to a significant degree (i.e. catalyst reactivation) byconducting the hydroformylation process in a reaction region where thehydroformylation reaction rate is of a negative or inverse order incarbon monoxide and one or more of the following: at a temperature suchthat the temperature difference between reaction product fluidtemperature and inlet coolant temperature is less than about 25° C.,preferably less than about 20° C., and more preferably less than about15° C.; at a carbon monoxide conversion of less than about 90%,preferably less than about 75%, and more preferably less than about 65%;at a hydrogen conversion of greater than about 65%, preferably greaterthan about 85%, and more preferably greater than about 90%; and/or at anolefinic unsaturated compound conversion of greater than about 50%,preferably greater than about 60%, and more preferably greater thanabout 70%. More preferably such intrinsic catalyst deactivation can beprevented or at least greatly minimized by conducting thehydroformylation process in a reaction region where the hydroformylationreaction rate is of a negative or inverse order in carbon monoxide and acombination of one or more of the following: at a temperature such thatthe temperature difference between reaction product fluid temperatureand inlet coolant temperature is less than about 25° C., preferably lessthan about 20° C., and more preferably less than about 15° C.; at acarbon monoxide conversion of less than about 90%, preferably less thanabout 75%, and more preferably less than about 65%; at a hydrogenconversion of greater than about 65%, preferably greater than about 85%,and more preferably greater than about 90%; and/or at an olefinicunsaturated compound conversion of greater than about 50%, preferablygreater than about 60%, and more preferably greater than about 70% priorto any significant build-up of such organomonophosphite byproducts (e.g.employing such negative or inverse order in carbon monoxide andpermissible combinations from the start of the hydroformylationprocess).

The carbon monoxide partial pressure of the hydroformylation processesof this invention is such that hydroformylation reaction rate increasesas carbon monoxide partial pressure decreases and hydroformylationreaction rate decreases as carbon monoxide partial pressure increases,i.e., the hydroformylation reaction rate is of a negative or inverseorder in carbon monoxide. The carbon monoxide partial pressure issufficient to prevent and/or lessen coordination of theorganomonophosphite ligand with the metal-organopolyphosphite ligandcomplex catalyst. As indicated herein, the carbon monoxide partialpressure is preferably from about 1 psia to about 1000 psia, morepreferably from about 3 psia to about 800 psia, and most preferably fromabout 5 psia to about 500 psia.

In contrast to metal-organopolyphosphite ligand complex catalyzedhydroformylation processes, carbon monoxide partial pressure is keptrelatively low in the conventional triphenylphosphine-modified rhodiumhydroformylation processes because higher linear to branched aldehyderatios are obtained (J. Falbe "New Syntheses with Carbon Monoxide,Springer Verlag, Berlin Heidelberg New York, 1980. p 55.) and tominimize catalyst deactivation through the formation of relativelyinactive rhodium clusters (see, for example, U.S. Pat. No. 4,277,627).

Aldehyde isomer ratios produced by organopolyphosphite modified metalcatalysts do not have the same sensitivity to carbon monoxide as dotriphenylphosphine-modified metal catalysts. With organopolyphosphitemodified metal catalysts, very high isomer ratios can be achieved in theregion where carbon monoxide is of negative reaction order. In addition,the organopolyphosphite modified metal catalysts do not undergo the typeof catalyst deactivating clustering reactions characteristic oftriphenylphosphine-modified metal catalysts. Thus one is not limited byconsiderations of isomer ratio or of metal, e.g., rhodium, clustering tooperating in the lower carbon monoxide partial pressure ranges.

When the rate of hydroformylation is graphically depicted as a functionof carbon monoxide partial pressure, the resulting curve passes througha maximum as set out in FIG. 1. In the rising part of the curve,hydroformylation has a positive order in carbon monoxide, on thedescending part of the curve, hydroformylation has a negative order incarbon monoxide.

Where the reaction is of positive order in carbon monoxide, an increasein hydroformylation reaction rate will decrease the partial pressure ofcarbon monoxide. This decrease in concentration will slow the rate suchthat the reaction temperature and carbon monoxide and hydrogen partialpressures can be easily controlled.

Conversely, when hydroformylation has an inverse or negative order incarbon monoxide, then as carbon monoxide is consumed, that which remainsis at a lower partial pressure and has a greater propensity to react. Asmore carbon monoxide is consumed, the hydroformylation reaction goeseven faster. In addition to the rate increase from decreasing carbonmonoxide partial pressure, there will also be an increase in rate fromthe heat of reaction since hydroformylation is an exothermic reaction. Afeedback loop develops which can result in essentially completeconsumption of the limiting reactant and therefore termination of thehydroformylation reaction.

The amount of inhibiting organomonophosphite free in solution can beincreased by increasing carbon monoxide partial pressure. Carbonmonoxide competes with the inhibiting organomonophosphite for the freecoordination site on the metal, e.g., rhodium, thereby increasing theconcentration of inhibiting organomonophosphite in solution.

If hydroformylation is operated under conditions of a positive order incarbon monoxide, a steadily declining catalyst activity is observedbecause of the accumulation of inhibitingorganomonophosphite/organopolyphosphite ligand-metal complex.Alternatively, if hydroformylation is operated at higher carbon monoxidepartial pressures in a region where hydroformylation has a negativeorder in carbon monoxide in order to dissociate inhibiting complexand/or prevent or lessen coordination of the organomonophosphite ligandwith the metal-organopolyphosphite ligand complex catalyst andfacilitate its hydrolysis, then the hydroformylation is operated in areaction region where control of carbon monoxide partial pressure,hydrogen partial pressure, total reaction pressure, hydroformylationreaction rate and/or temperature is more difficult.

Hydroformylation reaction rate may cycle during continuous operation ina continuous stirred type reactor as may carbon monoxide partialpressure, hydrogen partial pressure, total reaction pressure,hydroformylation reaction rate and/or temperature if one ishydroformylating under conditions where the reaction is of negative orinverse order in carbon monoxide. Cycling conditions disrupt steadyoperation of the unit. Uniform partial pressures and temperature aredesired. As used herein, "cycling" refers to frequent periodic andextreme changes in process parameters, e.g., reaction rate, reactiontemperature, total reaction pressure, carbon monoxide partial pressureand hydrogen partial pressure, during the hydroformylation process.

The cycling may be initiated when operating under conditions were therate of hydroformylation is inverse order in carbon monoxide. Theseconditions are not normally encountered with conventionaltriphenylphosphine-modified metal catalysts since the region wherecarbon monoxide is of negative rate order is also a region which giveslower isomer ratios and increased catalyst deactivation. Conventionaltriphenylphosphine-modified metal catalysts typically operate underconditions where increasing carbon monoxide partial pressure increasesreaction rate and conversely decreasing carbon monoxide partial pressuredecreases rate.

Higher carbon monoxide partial pressures provide desired benefits inorganopolyphosphite modified metal catalysts in that olefin efficiencylosses due to hydrogenation may be reduced and the dissociation of aninhibiting organomonophosphite from the catalyst is favored. Thedissociated or uncoordinated inhibiting organomonophosphite is morereadily hydrolyzed and the hydrolysis fragments can be scrubbed from thesolution as disclosed herein. Higher carbon monoxide partial pressuresgive both a higher lined out activity and lower efficiency losses toalkanes since the higher carbon monoxide partial pressure makes it amore effective competitor for a metal, e.g., rhodium, alkyl. If carbonmonoxide reacts with the metal, e.g., rhodium, alkyl, the acyl precursorof the aldehyde is obtained; if hydrogen reacts with the metal, e.g.,rhodium, alkyl, the corresponding alkane is obtained. However, asindicated above, operating at the higher carbon monoxide partialpressures where hydroformylation is of a negative order significantlycomplicates control of partial pressures.

It is normally desirable to increase the temperature difference betweenthe reaction temperature and the reactor cooling means, e.g., coolant,so that the equipment size can be minimized. Some have disclosed runningat reactor temperatures hot enough to generate useful steam from theexothermic heat of reaction. A typical non-aqueous triphenylphosphinesystem will have a temperature difference of approximately 30° C.between the reaction and the coolant.

Design of the heat removal equipment is an important aspect ofcontrolling the reaction partial pressures in this invention where theprocess is operated in inverse or negative order in carbon monoxide. Thetemperature difference between the reaction product fluid temperatureand the inlet coolant temperature should be small to provide to providethe necessary control. The lower the temperature difference the betterthe control will be. For hydroformylation in regions where the reactionis of a negative order in carbon monoxide, the difference should bebelow 25° C. and more preferably below 20° C. Temperature differencebelow 15° C. may be achieved using such as evaporative cooling, enhancedheat transfer or larger equipment.

Continuous stirred tank reactors used for exothermic reactions must havesome means of removing the heat of reaction from the reactor. Thecooling can be accomplished in a number of ways, putting a coolingjacket around the reactor, installing cooling coils in the reactor, orpumping the reactor solution through an external heat exchanger. In allcases the driving force for the heat removal is the temperaturedifference between the reaction product fluid and the reactor zonecoolant.

Most chemical reactions are affected by temperature, and by some or allof the reactant concentrations. If a catalyst is used, its concentrationalso will affect the reaction rate. In most circumstances it isdesirable to control the conditions in the reactor at some steady state.Changes in conditions may cause undesirable changes in selectivity,catalyst performance or other operational difficulties. Temperature hasan exponential effect on the hydroformylation reaction rate. A change inreaction temperature of 10° C. typically doubles the rate of reaction.If the reaction rate increases, the heat generated increases, and theextra heat must be removed to keep the temperature from continuing toincrease.

Removal of heat from a system is described by the following equation:

    Heat Removed=UAΔT

wherein U is a heat transfer coefficient dependent on the conditions onboth the process and coolant sides of the equipment, A is the surfacearea available for heat transfer, and ΔT is the appropriate temperaturedifference between the reaction product fluid temperature and inletcoolant temperature. At steady state,

    Heat Removed=Heat Generated by the reaction.

As an illustration, assume a reaction is only dependent on reactiontemperature. If for some reason the reactor temperature increases by 1°C., the reaction rate will increase by approximately 10% which will inturn generate 10% more heat. If nothing is changed with the reactionzone cooler, the heat removed will depend on the new AT of the system.If the original ΔT was 5C°., the new ΔT will be 6° C., a 20% (i.e. 1/5)increase in heat removed which tends to drive the system back to theoriginal set of steady conditions.

If instead of a 5° C. ΔT between reaction product fluid and reactionzone coolant, e.g., heat exchanger, the ΔT was 20C°., a 1° C. increasein reactor temperature will give a new temperature difference betweenreaction product fluid and reaction zone coolant, e.g., heat exchanger,of 21° C. Whereas the reaction rate increased by 10%, there was only a5% (i.e. 1/20) increase in the heat removal capability. Since more heatis being generated than is being removed, the reactor would continue towarm until some action is taken to increase the heat transfer from thesystem or until the reactant(s) were exhausted.

When carbon monoxide is of negative order, in order to have anintrinsically stable system, a disturbance in the temperature mustproduce a smaller percentage increase in reaction rate than thepercentage increase in ΔT of the system. As used herein, "inlet coolanttemperature" refers to the temperature of the coolant prior to enteringany heat transfer means, e.g., internal coils, external jackets, shelland tube heat exchanger, plate and frame heat exchanger and the like.This invention is not intended to be limited in any manner by thepermissible coolants and/or heat transfer means.

Commercial systems are more complicated in that the reaction ratedepends on reactant and catalyst concentrations as well as temperature.Furthermore, the reaction rate may increase with an increase inconcentration of one reactant and decrease with an increase inconcentration of another reactant. When the reaction rate changes arethe same sign as the concentration changes, the concentration changeshelp the stability of the operation. If a disturbance in the systemcauses the rate to increase, more reactant is consumed which in turnmakes the rate slow down bringing it back toward a steady state. Incontrast, systems where the reaction rate increases with a decrease inreactant concentration are more difficult to control. Rate increasesconsume more reactant which causes the rate to increase even consumingmore of the reactant. As a result the ΔT of the heat exchanger will haveto be lower to produce intrinsic stability than it would for a systemwhere the reactants had no effect on reaction rate. These effects willvary in magnitude with the kinetic responses of the different reactants.

The effect of the feedback loop described above created by the negativeor inverse order in carbon monoxide can be minimized by keeping theconversion of the carbon monoxide low in a given reaction stage.Disturbances in the carbon monoxide feed or the reaction rate are asmaller portion of the total carbon monoxide exiting the reaction stagewhen the conversion is low. As a result, the disturbance has a smallerfeedback effect on the reaction system.

For example, given that stoichiometric amounts of olefin, hydrogen andcarbon monoxide are fed to a reactor, and the total molar feed to thereactor is 3 lb. moles/hr., if the conversion in the reactor is 50%, 0.5lb. mole of carbon monoxide will exit the reactor. If a disturbance inthe carbon monoxide feed causes a momentary increase of 0.1 lb. mole,the amount of carbon monoxide will increase by no more than 0.1/0.5 or20% immediately after the disturbance. If, however, the conversion inthe reactor was 80%, the disturbance could potentially be 0.1/0.2 or 50%of the exiting carbon monoxide. The 50% response for the high conversioncase would produce a more significant feedback response than the lowerconversion case of 20%. Hence, the lower the carbon monoxide conversion,the more stability will be imparted to the reaction system.

In order to consume excess reactant, carbon monoxide must either berecycled back to the reaction system or the portion of the reactant thatis not converted to the product in the stages with control difficultiesmust be converted in subsequent reaction vessels or stages. The aboveexample uses carbon monoxide as the reactant with the hydroformylationreaction rate of a negative or inverse order in carbon monoxide. Anyreactant that has a negative effect on the reaction rate will behave ina similar manner. Lower conversions of the negative order reactant willprovide for more stable operation of the reaction system.

As a result of this invention, more stability will be imparted to ahydroformylation reaction vessel or stage by employing one or more of alow ΔT, low carbon monoxide conversions, high hydrogen conversions andhigh olefinic unsaturated compound conversions in hydroformylationprocesses that are conducted in reaction regions where thehydroformylation reaction rate is of a negative or inverse order incarbon monoxide. A carbon monoxide conversion of less than about 90%,preferably less than about 75%, and more preferably less than about 65%,may be employed in the processes of this invention to produce a stablereaction system.

The hydroformylation reaction can be controlled by limiting the amountof hydrogen fed to the reaction system. If the hydroformylation reactionis consuming essentially all of the hydrogen fed to the reactor, thereaction rate cannot increase. It is limited by the availability ofhydrogen.

The hydrogen partial pressure exiting the reactor should be very low tosuccessfully control the reaction. As hydrogen feed is limited, the rateof aldehyde production will begin to be governed by mass transfereffects rather than pure kinetics. Mass transfer in a vapor liquidmedium is proportional to the concentration of the reactant in thevapor. In the limit, the hydroformylation reaction rate must be zerowhen no hydrogen is present because it is an essential reactant. A largepositive effect on rate by a reactant concentration is beneficial forcontrolling the conditions in the reactor. As the rate increases, thereactant is consumed which slows down the rate. If the rate slows down,the concentration of the reactant increases which tends to increase thereaction rate. This is depicted by the following equation:

    Mass Transfer rate=Constant×(concentration of hydrogen in vapor)

In principle, the hydroformylation reaction could be limited bythrottling any one of the reactants, olefin, carbon monoxide orhydrogen. However, limiting the olefin would mean the reaction systemwould have to be very large to produce commercial quantities of product.Limiting the carbon monoxide feed to the reactor would allow undesirableside reactions to occur with the ligand as described earlier. Hydrogenis the best component to use as the limiting reactant for this system.

When the hydroformylation reaction rate is limited by mass transfer, thereaction rate cannot increase significantly because it is limited by therate which the hydrogen can be transported to the active catalyst site.Even if the rate were not limited by the rate of transport, the maximumincrease in reaction rate is bound by the excess hydrogen that isexiting the reactor. If the excess of hydrogen is very small, thepossible increase in rate is very small. The hydroformylation reactionrate can only increase until it consumes all, or essentially all, of thehydrogen entering the reactor.

For example, if 99.5% of the hydrogen fed to a reactor is converted toaldehyde, the possible increase in reaction rate is only 0.005×(Feedrate of hydrogen). If the conversion of hydrogen were only 97.5%, therate could increase by 0.025×(Feed rate of hydrogen) producing adisturbance five times the size of the disturbance where the conversionwas 99.5%. The best hydrogen conversion for operation will depend on thekinetics of the system.

As used herein, conversions refer to conversions in an individualreactive stage. Within an individual reactive stage, a liquid or gaselement within that stage will have essentially the same composition asa liquid or gas element taken from some other region of the reactivestage. A separate reactive stage is said to exist when some type ofbarrier whether physical or mechanical allows a difference incomposition between a representative element from each stage, orcatalyst product fluid zone, where reactants and catalysts are presenttogether under reaction conditions described herein. Certain"non-idealities" will occur within a single reactive stage such as nearthe inlet point of the reactants. This definition of a reactive stage isnot meant to include such non-idealities. The definition of a reactivestage does not imply that the stages have no mixing between them. Somebackmixing between the stages may occur diminishing the efficiency of asingle reactive stage, but the stages are still distinct. One or morereactive stages may be present in a reactive zone.

As a result of this invention, more stability will be imparted to ahydroformylation reaction vessel or stage by employing one or more of alow ΔT, low carbon monoxide conversions, high hydrogen conversions andhigh olefinic unsaturated compound conversions in hydroformylationprocesses that are conducted in reaction regions where thehydroformylation reaction rate is of a negative or inverse order incarbon monoxide. A hydrogen conversion of greater than about 65%,preferably greater than about 85%, and more preferably greater thanabout 90%, may be employed in the processes of this invention to producea stable reaction system.

The hydroformylation rate is approximately of first order with respectto the olefin partial pressure in the reaction vessel. When adisturbance in reaction conditions increases the reaction rate, theamount of olefin in the reaction vessel will decrease. A decrease inolefin concentration will slow the hydroformylation rate which tends topush the system back to the steady-state that it was at before thedisturbance. Likewise, a disturbance in the reaction rate that slows thereaction will tend to increase the amount of olefin in the reactionvessel. The increase in olefin concentration has the effect ofincreasing the hydroformylation rate which also tends to push the systemback toward the original steady-state. However, depending on therelative concentration of reactants in the vessel, the concentration ofolefin may or may not change significantly. If a large excess of olefinis present in the reaction vessel such as when operating at low olefinconversions, the amount of olefin present in the reaction vessel maychange little even when a relatively large disturbance in the reactioncondition occurs. Another condition favorable to the olefin acting as astabilizing influence could be when the conversion of the olefin is low,but the concentration of the olefin in the reaction system is also low.Under either of these conditions, a change in reaction rate during anupset in reaction conditions produces a similarly significant change inthe olefin present in the reaction vessel. If the amount of olefin inthe reaction vessel does not change significantly, its ability to behaveas a stabilizing influence is diminished. One disadvantage of keepingthe olefin concentration low and the conversion low is that theequipment used to produce the same amount of product will be larger thanthe situation where the olefin conversion is high.

For the purposes of this invention, the conversion of the olefin shouldbe greater than about 70%, preferably greater than about 80%, and morepreferably greater than about 85%. The benefits of stabilization fromthe olefin can be combined with other operating conditions such astemperature difference between the process and the coolant, hydrogenconversion, and low carbon monoxide conversion (high carbon monoxidepartial pressures), and high hydrogen partial pressures (low hydrogenconversion). By combining one or more of the techniques, an operableregion may be found without going to an extreme in any one of theconditions.

It should also be understood that much of the necessary total conversionof the olefin could be performed in reaction vessels or compartmentspreceding the vessel of interest. The olefin conversion within a givencompartment may be greater than about 50%, preferably greater than about60%, and more preferably greater than about 70%. However, the olefin canstill have a stabilizing influence on the reaction conditions if theolefin concentration changes significantly with a correspondingsignificant change in reaction conditions. This is a similar situationas described above where the olefin conversion is low, but theconcentration of the olefin in the particular vessel is also low.

The reaction rate may increase with an increase in concentration of onereactant and decrease with an increase in concentration of anotherreactant. When the reaction rate changes are the same sign as theconcentration changes, the concentration changes help the stability ofthe operation. If a disturbance in the system causes the rate toincrease, more reactant is consumed which in turn makes the rate slowdown bringing it back toward a steady state. In contrast, systems wherethe reaction rate increases with a decrease in reactant concentrationare more difficult to control. Rate increases consume more reactantwhich causes the rate to increase even consuming more of the reactant.As a result the ΔT of the heat exchanger will have to be lower toproduce intrinsic stability than it would for a system where thereactants had no effect on reaction rate. These effects will vary inmagnitude with the kinetic responses of the different reactants.

In addition to the stabilizing effect conversion can have on thehydroformylation reaction system, the system can also have stabilityimparted to it simply by the kinetic response of the system. The kineticresponse of an organopolyphosphite to carbon monoxide partial pressurefor a significant range of carbon monoxide pressures is negative. Inother words, for a given change in carbon monoxide partial pressure, thereaction rate will respond in the opposite direction; an increase incarbon monoxide partial pressure causing a decrease in rate, or adecrease in carbon monoxide partial pressure causing an increase inrate. It is possible to represent this negative response empirically bysaying the reaction rate is a function of the carbon monoxide partialpressure raised to some power "b". The kinetic response may not alwaysbehave in this manner, but it can be a very useful way of representingthe reaction rate over some portion of the operating conditions. If "b"is less than zero, the rate is said to be negative order in carbonmonoxide and, if "b" is less than zero, the change in reaction rate fora fixed change in carbon monoxide partial pressure will decrease as thepartial pressure of carbon monoxide increases. For example if thereaction rate is proportional to the carbon monoxide partial pressureraised to the "-1" power, a change from 30 to 40 psi carbon monoxideresults in a relative change in reaction rate of 1.33, whereas a changefrom 100 to 110 psi carbon monoxide results in a relative change inreaction rate of 1.10. This response is due only to the conditionswithin the reactor, and is not dependent on the conversion of anyparticular reactant. All of the reactants may affect the reaction ratewhether positive or negative order, but the exact responses will dependon the specific kinetic response for a particular catalyst and aparticular reactant.

The subject invention may be useful in conjunction with anotherinvention which resides in the discovery that deactivation ofmetal-organopolyphosphite ligand complex catalysts caused by aninhibiting or poisoning organomonophosphite can be reversed or at leastminimized by carrying out hydroformylation processes in a reactionregion where the hydroformylation reaction rate is of a negative orinverse order in carbon monoxide and at a temperature such that thetemperature difference between reaction product fluid temperature andinlet coolant temperature is sufficient to prevent and/or lessen cyclingof carbon monoxide partial pressure, hydrogen partial pressure, totalreaction pressure, hydroformylation reaction rate and/or temperatureduring said hydroformylation process. Such invention is disclosed incopending U.S. patent application Ser. No. (08/757,744), filed on aneven date herewith, the disclosure of which is incorporated herein byreference.

The hydroformylation processes encompassed by this invention are alsoconducted in the presence of an organic solvent for themetal-organopolyphosphite ligand complex catalyst and freeorganopolyphosphite ligand. The solvent may also contain dissolved waterup to the saturation limit. Depending on the particular catalyst andreactants employed, suitable organic solvents include, for example,alcohols, alkanes, alkenes, alkynes, ethers, aldehydes, higher boilingaldehyde condensation byproducts, ketones, esters, amides, tertiaryamines, aromatics and the like. Any suitable solvent which does notunduly adversely interfere with the intended hydroformylation reactioncan be employed and such solvents may include those disclosed heretoforecommonly employed in known metal catalyzed hydroformylation reactions.Mixtures of one or more different solvents may be employed if desired.In general, with regard to the production of achiral (non-opticallyactive) aldehydes, it is preferred to employ aldehyde compoundscorresponding to the aldehyde products desired to be produced and/orhigher boiling aldehyde liquid condensation byproducts as the mainorganic solvents as is common in the art. Such aldehyde condensationbyproducts can also be preformed if desired and used accordingly.Illustrative preferred solvents employable in the production ofaldehydes include ketones (e.g. acetone and methylethyl ketone), esters(e.g. ethyl acetate), hydrocarbons (e.g. toluene), nitrohydrocarbons(e.g. nitrobenzene), ethers (e.g. tetrahydrofuran (THF) and glyme),1,4-butanediols and sulfolane. Suitable solvents are disclosed in U.S.Pat. No. 5,312,996. The amount of solvent employed is not critical tothe subject invention and need only be that amount sufficient tosolubilize the catalyst and free ligand of the hydroformylation reactionmixture to be treated. In general, the amount of solvent may range fromabout 5 percent by weight up to about 99 percent by weight or more basedon the total weight of the hydroformylation reaction mixture startingmaterial.

Accordingly illustrative non-optically active aldehyde products includee.g., propionaldehyde, n-butyraldehyde, isobutyraldehyde,n-valeraldehyde, 2-methyl 1-butyraldehyde, hexanal, hydroxyhexanal,2-methyl valeraldehyde, heptanal, 2-methyl 1-hexanal, octanal, 2-methyl1-heptanal, nonanal, 2-methyl-1-octanal, 2-ethyl 1-heptanal, 3-propyl1-hexanal, decanal, adipaldehyde, 2-methylglutaraldehyde,2-methyladipaldehyde, 3-methyladipaldehyde, 3-hydroxypropionaldehyde,6-hydroxyhexanal, alkenals, e.g., 2-, 3- and 4-pentenal, alkyl5-formylvalerate, 2-methyl-1-nonanal, undecanal, 2-methyl 1-decanal,dodecanal, 2-methyl 1-undecanal, tridecanal, 2-methyl 1-tridecanal,2-ethyl, 1-dodecanal, 3-propyl-1-undecanal, pentadecanal,2-methyl-1-tetradecanal, hexadecanal, 2-methyl-1-pentadecanal,heptadecanal, 2-methyl-1-hexadecanal, octadecanal,2-methyl-1-heptadecanal, nonodecanal, 2-methyl-l-octadecanal, 2-ethyl1-heptadecanal, 3-propyl-1-hexadecanal, eicosanal,2-methyl-1-nonadecanal, heneicosanal, 2-methyl-1-eicosanal, tricosanal,2-methyl-1-docosanal, tetracosanal, 2-methyl-1-tricosanal, pentacosanal,2-methyl-1-tetracosanal, 2-ethyl 1-tricosanal, 3-propyl-1-docosanal,heptacosanal, 2-methyl-1-octacosanal, nonacosanal,2-methyl-1-octacosanal, hentriacontanal, 2-methyl-1-triacontanal, andthe like.

Illustrative optically active aldehyde products include (enantiomeric)aldehyde compounds prepared by the asymmetric hydroformylation processof this invention such as, e.g. S-2-(p-isobutylphenyl)-propionaldehyde,S-2-(6-methoxy-2-naphthyl)propionaldehyde,S-2-(3-benzoylphenyl)-propionaldehyde,S-2-(p-thienoylphenyl)propionaldehyde,S-2-(3-fluoro-4-phenyl)phenylpropionaldehyde, S-2-4-(1,3-dihydro-1-oxo-2H-isoindol-2-yl)phenyl!propionaldehyde,S-2-(2-methylacetaldehyde)-5-benzoylthiophene and the like.

Illustrative of suitable substituted and unsubstituted aldehyde productsinclude those permissible substituted and unsubstituted aldehydecompounds described in Kirk-Othmer, Encyclopedia of Chemical Technology,Fourth Edition, 1996, the pertinent portions of which are incorporatedherein by reference.

As indicated above, it is generally preferred to carry out thehydroformylation processes of this invention in a continuous manner. Ingeneral, continuous hydroformylation processes are well known in the artand may involve: (a) hydroformylating the olefinic starting material(s)with carbon monoxide and hydrogen in a liquid homogeneous reactionmixture comprising a solvent, the metal-organopolyphosphite ligandcomplex catalyst, and free organopolyphosphite ligand; (b) maintainingreaction temperature and pressure conditions favorable to thehydroformylation of the olefinic starting material(s); (c) supplyingmake-up quantities of the olefinic starting material(s), carbon monoxideand hydrogen to the reaction medium as those reactants are used up; and(d) recovering the desired aldehyde hydroformylation product(s) in anymanner desired. The continuous process can be carried out in a singlepass mode, i.e., wherein a vaporous mixture comprising unreactedolefinic starting material(s) and vaporized aldehyde product is removedfrom the liquid reaction mixture from whence the aldehyde product isrecovered and make-up olefinic starting material(s), carbon monoxide andhydrogen are supplied to the liquid reaction medium for the next singlepass without recycling the unreacted olefinic starting material(s). Suchtypes of recycle procedure are well known in the art and may involve theliquid recycling of the metal-organopolyphosphite complex catalyst fluidseparated from the desired aldehyde reaction product(s), such asdisclosed, for example, in U.S. Pat. No. 4,148,830 or a gas recycleprocedure such as disclosed, for example, in U.S. Pat. No. 4,247,486, aswell as a combination of both a liquid and gas recycle procedure ifdesired. The disclosures of said U.S. Pat. Nos. 4,148,830 and 4,247,486are incorporated herein by reference thereto. The most preferredhydroformylation process of this invention comprises a continuous liquidcatalyst recycle process. Suitable liquid catalyst recycle proceduresare disclosed, for example, in U.S. Pat. Nos. 4,668,651; 4,774,361;5,102,505 and 5,110,990.

In an embodiment of this invention, the aldehyde product mixtures may beseparated from the other components of the crude reaction mixtures inwhich the aldehyde mixtures are produced by any suitable method.Suitable separation methods include, for example, solvent extraction,crystallization, distillation, vaporization, wiped film evaporation,falling film evaporation, phase separation, filtration and the like. Itmay be desired to remove the aldehyde products from the crude reactionmixture as they are formed through the use of trapping agents asdescribed in published Patent Cooperation Treaty Patent Application WO88/08835. A preferred method for separating the aldehyde mixtures fromthe other components of the crude reaction mixtures is by membraneseparation. Such membrane separation can be achieved as set out in U.S.Pat. No. 5,430,194 and copending U.S. patent application Ser. No.08/430,790, filed May 5, 1995, referred to above.

As indicated above, at the conclusion of (or during) the process of thisinvention, the desired aldehydes may be recovered from the reactionmixtures used in the process of this invention. For example, therecovery techniques disclosed in U.S. Pat. Nos. 4,148,830 and 4,247,486can be used. For instance, in a continuous liquid catalyst recycleprocess the portion of the liquid reaction mixture (containing aldehydeproduct, catalyst, etc.), i.e., reaction product fluid, removed from thereaction zone can be passed to a separation zone, e.g.,vaporizer/separator, wherein the desired aldehyde product can beseparated via distillation, in one or more stages, under normal, reducedor elevated pressure, from the liquid reaction fluid, condensed andcollected in a product receiver, and further purified if desired. Theremaining non-volatilized catalyst containing liquid reaction mixturemay then be recycled back to the reactor as may any other volatilematerials, e.g., unreacted olefin, together with any hydrogen and carbonmonoxide dissolved in the liquid reaction after separation thereof fromthe condensed aldehyde product, e.g., by distillation in anyconventional manner. In general, it is preferred to separate the desiredaldehydes from the catalyst-containing reaction mixture under reducedpressure and at low temperatures so as to avoid possible degradation ofthe organopolyphosphite ligand and reaction products. When analpha-mono-olefin reactant is also employed, the aldehyde derivativethereof can also be separated by the above methods.

More particularly, distillation and separation of the desired aldehydeproduct from the metal-organopolyphosphite complex catalyst containingreaction product fluid may take place at any suitable temperaturedesired. In general, it is recommended that such distillation take placeat relatively low temperatures, such as below 150° C., and morepreferably at a temperature in the range of from about 50° C. to about140° C. It is also generally recommended that such aldehyde distillationtake place under reduced pressure, e.g., a total gas pressure that issubstantially lower than the total gas pressure employed duringhydroformylation when low boiling aldehydes (e.g., C₄ to C₆) areinvolved or under vacuum when high boiling aldehydes (e.g. C₇ orgreater) are involved. For instance, a common practice is to subject theliquid reaction product medium removed from the hydroformylation reactorto a pressure reduction so as to volatilize a substantial portion of theunreacted gases dissolved in the liquid medium which now contains a muchlower synthesis gas concentration than was present in thehydroformylation reaction medium to the distillation zone, e.g.vaporizer/separator, wherein the desired aldehyde product is distilled.In general, distillation pressures ranging from vacuum pressures on upto total gas pressure of about 50 psig should be sufficient for mostpurposes.

As indicated above, once the inhibiting organomonophosphite byproduct isdissociated from the metal-organopolyphosphite ligand complex catalystor otherwise in solution, treatment with water and/or weakly acidicadditives causes the undesirable organomonophosphite ligand byproduct tohydrolyze at a much faster rate than the desired organopolyphosphiteligand employed. A water and/or weakly acidic additive treatment allowsone to selectively remove such undesired organomonophosphite byproductsfrom the reaction system or more preferably prevent or minimize anyundue adverse buildup of such organomonophosphite ligand byproductwithin the reaction system as described below.

Weakly acidic additives which are employable herein and which are addedto the hydroformylation reaction medium are well known compounds as aremethods for their preparation and in general are readily commerciallyavailable. Any weakly acidic compound having a pKa value of from about1.0 to about 12 and more preferably from about 2.5 to about 10 may beemployed herein. The slightly acidic nature of such compounds has beenfound to catalyze the hydrolysis of the organomonophosphite ligandbyproduct, even when no additional water is deliberately added to thehydroformylation reaction medium, without unduly adversely affecting theorganopolyphosphite ligand employed. For example, the acidity of theadditive compound should not be so high as to also destroy theorganopolyphosphite ligand by acid hydrolysis at an unacceptable rate.Such pKa values are a measure of the acidity of a compound as given interms of the negative (decadic) logarithm of the acidic dissociationconstant, i.e., -log₁₀ Ka=pKa as defined in "Lange's Handbook ofChemistry", Thirteenth Edition, J. A. Dean Editor, pp 5-18 to 5-60(1985); McGraw-Hill Book Company. Of course estimated pKa values may beobtained by making a comparison with compounds of recognizably similarcharacter for which pKa values are known as discussed on page 5-13 ofsaid "Lange's Handbook of Chemistry".

Among the more preferred weakly acidic compounds are aryl compoundscontaining from 1 to 3 substituent radicals directly bonded thereto(i.e. directly attached to the aryl ring of said aryl compounds asopposed to being bonded to some substituent of said aryl compounds),each said substituent radical being individually selected from the groupconsisting of hydroxy and carboxylic acid radicals. Such aryl compoundsinclude those selected from the group consisting of phenyl, biphenyl,naphthyl and dinaphthyl compounds as well as heterocyclic type arylcompounds such as pyridine, and the like. Preferably such weakly acidiccompounds contain from 1 to 2 hydroxy radicals or 1 to 2 carboxylic acidradicals or mixtures thereof. Of course, if desired such weakly acidicaryl compounds may also contain other groups or substituents which donot unduly adversely interfere with the purpose of this invention, suchas alkyl, halide, trifluoromethyl, nitro, and alkoxy radicals, and thelike.

When selecting a particular weakly acidic compound for use in a givenprocess of this invention, in addition to the pKa value of the weaklyacidic compound, one may also wish to consider its overall catalyticperformance in conjunction with the many particulars of thehydroformylation process involved, e.g. the particular olefin to behydroformylated, the particular aldehyde product and aldehyde productisomer ratio desired, the organopolyphosphite ligand employed, theamount of water present in the reaction medium, the amount oforganomonophosphite ligand present in the reaction medium, and the like,as well as such characteristics of the weakly acidic compound additiveas its solubility in the hydroformylation reaction medium and itsvolatility (e.g. boiling point), etc.

Of course it is to be understood that such weakly acidic compoundadditives may be employed individually or as mixtures of two or moredifferent weakly acidic compounds. Moreover the amount of such weaklyacidic compound additives employable in any given process of thisinvention need only be a catalytic amount i.e. that minimum amountnecessary to catalyze the selective hydrolysis of theorganomonophosphite ligand byproduct. Amounts of such weakly acidiccompound additives of from 0 to about 20 weight percent or higher ifdesired, based on the total weight of the hydroformylation reactionmedium may be employed. In general, when employed, it is preferred toemploy amounts of such weakly acidic compound additives in the range offrom about 0.1 to about 5.0 weight percent based on the total weight ofthe hydroformylation reaction medium. More preferably thehydroformylation process of this invention is carried out in the absenceof any such weakly acidic compound additives.

Indeed it has been found that merely by deliberately providing thehydroformylation reaction medium with a small amount of added water onecan selectively hydrolyze the undesirable organomonophosphite ligandbyproduct at a suitably acceptable rate without unduly adverselyhydrolyzing the desired organopolyphosphite ligand employed. Forinstance, by providing the hydroformylation reaction medium of theprocess of this invention with a suitable amount of added water rightfrom the start of the hydroformylation process (or at least before anyundue adverse build-up of organomonophosphite ligand byproduct has takenplace) one can selectively hydrolyze (without the need of any weaklyacidic compound additive) the undesirable organomonophosphite ligandbyproduct as it being formed in situ and thereby prevent or minimize anyundue adverse build-up of said organomonophosphite ligand. Suchselective hydrolysis in turn prevents or minimizes the intrinsicmetal-organopolyphosphite ligand complex catalyst deactivation caused bysuch organomonophosphite ligand as previously discussed herein.

The term "added water" as employed herein refers to water that has beendeliberately supplied to the hydroformylation reaction system (asopposed to the presence of only in situ produced water in thehydroformylation reaction medium) of the subject invention. As notedabove it may not be necessary to employ any such added water in theprocess of the subject invention, since hydrolysis of theorganomonophosphite ligand byproduct, due to the presence of only insitu produced water in the reaction medium, may be satisfactorilycatalyzed by the use of a weakly acidic compound additive provided thatthe amount of organomonophosphite ligand present is not too great. Thus,it is preferred to carry out the hydroforinylation process of thesubject invention in the presence of a suitable amount of added waterregardless of whether a weakly acidic compound additive is alsoemployed.

Accordingly, the amount of such added water employable in any givenprocess of this invention need only be that minimum amount necessary toachieve the desired selective hydrolysis of the organomonophosphiteligand byproduct. Amounts of such added water of from 0 to about 20weight percent, or higher if desired, based on the total weight of thehydroformylation reaction medium may be employed. Of course amounts ofadded water that might also lead to adversely hydrolyzing the desiredorganopolyphosphite ligand at an undesirable rate are to be avoided.Amounts of water that may result in a two phase (organic-aqueous)hydroformylation reaction medium as opposed to the desired andconventional single phase (organic) homogeneous hydroformylationreaction medium are preferably to be avoided. In general, when employed,it is preferred to employ amounts of such added water in the range offrom about 0.05 to about 10 weight percent based on the total weight ofthe hydroformylation reaction medium.

The addition of the added water and/or weakly acidic compound additivesto the hydroformylation reaction medium of this invention may beaccomplished in any suitable manner desired and their order of additionis immaterial. For instance they may be added separately and/orsimultaneously, or premixed and then added if desired. Moreover, theymay be introduced into the reaction system on their own or along withany conventional reactant, e.g. along with the syn gas or olefinreactant, or via the catalyst recycle line. As noted it is preferred toemploy such added water and/or weakly acidic compound additive (whenindeed such is used) right from the start-up of the hydroformylationprocess. For example the weakly acidic compound additive may besolubilized in the metal, e.g., rhodium, catalyst precursor compositionand added to the reactor along with said composition, while water may bepreferably added to the reaction medium via water saturated syn gas,obtained e.g., by sparging syn gas through a container of water prior tointroducing the syn gas into the reactor. Thus an additional benefit ofthe subject invention is that conventional metal catalyzed continuoushydroformylation reaction systems do not have to be significantlymodified, if indeed they have to be modified at all, to accommodate thesubject invention.

The selective hydrolysis of the undesired organomonophosphite ligandbyproduct can take place in the same hydroformylation reactor andthroughout the continuous reaction system and under the samehydroformylation conditions employed to produce the desired aldehydeproduct from its olefinic starting material. Thus the conditionsemployed to effect the selective hydrolysis of the undesirableorganomonophosphite ligand byproduct are not critical and include any ofthe same conventional continuous hydroformylation conditions heretoforeemployed in the art. Such desired flexibility furnishes one with wideprocessing latitude for controlling and balancing the degree ofimprovement desired in preventing or minimizing the intrinsicdeactivation of the metal-organopolyphosphite ligand complex catalystcaused by the organomonophosphite ligand byproduct.

Hydrolysis of the organomonophosphite ligand byproduct in turn leads tothe formation of phosphorus acidic compounds, e.g., hydroxy alkylphosphonic acids, as outlined, for example, in U.S. Pat. No. 4,737,588.Moreover such phosphorus acidic compounds, e.g., hydroxy alkylphosphonic acids, are also undesirable in metal-organopolyphosphiteligand catalyzed hydroformylation processes as disclosed, for example,in U.S. Pat. Nos. 4,737,588 and 4,769,498. However the formation of suchphosphorus acidic compounds as a result of the hydrolysis of theorganomonophosphite ligand byproduct via the subject invention, is nonethe less, preferable to the continued presence of the more undesirableorganomonophosphite ligand byproduct in the hydroformylation process.Indeed it is considered that the presence of such phosphorus acidiccompounds, e.g., hydroxy alkyl phosphonic acid byproducts, may beeffectively controlled as described in said U.S. Pat. Nos. 4,737,588 and4,769,498 or as described herein.

Thus as pointed out herein, a noticeable decrease in the catalyticactivity of heretofore conventional continuous metal-organopolyphosphitecomplex catalyzed continuous hydroformylation processes has beenobserved to occur over time. This intrinsic loss in catalytic activitymanifests itself in terms of a measurable drop in productivity and isconsidered to be caused by in situ formation of an organomonophosphiteligand byproduct that poisons the metal-organopolyphosphite complexcatalyst as described herein. Accordingly this invention rests in thediscovery that such intrinsic catalyst deactivation in suchhydroformylation processes may be reversed or significantly minimized bycarrying out the hydroformylation process in a reaction region where thehydroformylation reaction rate is of a negative or inverse order incarbon monoxide and at a temperature such that the temperaturedifference between reaction product fluid temperature and inlet coolanttemperature is less than about 25° C.

For example, rhodium-bisphosphite ligand complex catalysts which havebecome partially deactivated due to the in situ build-up of undesirableorganomonophosphite ligand byproduct may have at least some of theircatalytic activity restored by the practice of this invention.Alternatively, it is preferred not to allow for any significantintrinsic catalyst deactivation due to in situ build-up of suchorganomonophosphite ligand byproduct in the hydroformylation reactionmedium, but rather to prevent or at least greatly minimize suchdeactivation from taking place in the first place by carrying out thehydroformylation process right from its start in a reaction region wherethe hydroformylation reaction rate is of a negative or inverse order incarbon monoxide and at a temperature such that the temperaturedifference between reaction product fluid temperature and inlet coolanttemperature is less than about 25° C. The resulting reaction productfluid is then treated with added water and/or weakly acidic compoundadditive, so as to hydrolyze any such undesirable organomonophosphiteligand at the rate that it is produced in situ to form phosphorus acidiccompounds.

As indicated above, a means for preventing or minimizing liganddegradation and catalyst deactivation and/or precipitation involvescarrying out the invention described and taught in copending U.S. patentapplication Ser. Nos. (08/756,501) and (08/753,505), both filed on aneven date herewith, the disclosures of which are incorporated herein byreference, which comprises using an aqueous buffer solution andoptionally organic nitrogen compounds as disclosed therein.

For instance, said aqueous buffer solution invention comprises treatingat least a portion of a metal-organopolyphosphite ligand complexcatalyst containing reaction product fluid derived from saidhydroformylation process and which also contains phosphorus acidiccompounds formed during said hydroformylation process, with an aqueousbuffer solution in order to neutralize and remove at least some amountof the phosphorus acidic compounds from said reaction product fluid, andthen returning the treated reaction product fluid to thehydroformylation reaction zone or separation zone. Illustrativephosphorus acidic compounds include, for example, H₃ PO₃, aldehyde acidssuch as hydroxy alkyl phosphonic acids, H₃ PO₄ and the like. Saidtreatment of the metal-organopolyphosphite ligand complex catalystcontaining reaction product fluid with the aqueous buffer solution maybe conducted in any suitable manner or fashion desired that does notunduly adversely affect the basic hydroformylation process from whichsaid reaction product fluid was derived.

Thus, for example, the aqueous buffer solution may be used to treat allor part of a reaction medium of a continuous liquid catalyst recyclehydroformylation process that has been removed from the reaction zone atany time prior to or after separation of the aldehyde product therefrom.More preferably said aqueous buffer treatment involves treating all orpart of the reaction product fluid obtained after distillation of asmuch of the aldehyde product desired, e.g. prior to or during therecycling of said reaction product fluid to the reaction zone. Forinstance, a preferred mode would be to continuously pass all or part(e.g. a slip stream) of the recycled reaction product fluid that isbeing recycled to the reaction zone through a liquid extractorcontaining the aqueous buffer solution just before said catalystcontaining residue is to re-enter the reaction zone.

Thus it is to be understood that the metal-organopolyphosphite ligandcomplex catalyst containing reaction product fluid to be treated withthe aqueous buffer solution may contain in addition to the catalystcomplex and its organic solvent, aldehyde product, free phosphiteligand, unreacted olefin, and any other ingredient or additiveconsistent with the reaction medium of the hydroformylation process fromwhich said reaction product fluids are derived.

Typically maximum aqueous buffer solution concentrations are onlygoverned by practical considerations. As noted, treatment conditionssuch as temperature, pressure and contact time may also vary greatly andany suitable combination of such conditions may be employed herein. Ingeneral liquid temperatures ranging from about 20° C. to about 80° C.and preferably from about 25° C. to about 60° C. should be suitable formost instances, although lower or higher temperatures could be employedif desired. Normally the treatment is carried out under pressuresranging from ambient to reaction pressures and the contact time may varyfrom a matter of seconds or minutes to a few hours or more.

Moreover, success in removing phosphorus acidic compounds from thereaction product fluid may be determined by measuring the ratedegradation (consumption) of the organopolyphosphite ligand present inthe hydroformylation reaction medium. In addition as the neutralizationand extraction of phosphorus acidic compounds into the aqueous buffersolution proceeds, the pH of the buffer solution will decrease andbecome more and more acidic. When the buffer solution reaches anunacceptable acidity level it may simply be replaced with a new buffersolution.

The aqueous buffer solutions employable in this invention may compriseany suitable buffer mixture containing salts of oxyacids, the nature andproportions of which in the mixture, are such that the pH of theiraqueous solutions may range from 3 to 9, preferably from 4 to 8 and morepreferably from 4.5 to 7.5. In this context suitable buffer systems mayinclude mixtures of anions selected from the group consisting ofphosphate, carbonate, citrate and borate compounds and cations selectedfrom the group consisting of ammonium and alkali metals, e.g. sodium,potassium and the like. Such buffer systems and/or methods for theirpreparation are well known in the art.

Preferred buffer systems are phosphate buffers and citrate buffers, e.g.monobasic phosphate/dibasic phosphates of an alkali metal and citratesof an alkali metal. More preferred are buffer systems consisting ofmixtures of the monobasic phosphate and the dibasic phosphate of sodiumor potassium.

Optionally, an organic nitrogen compound may be added to thehydroformylation reaction product fluid to scavenge the acidichydrolysis byproducts formed upon hydrolysis of the organopolyphosphiteligand, as taught, for example, in U.S. Pat. No. 4,567,306, copendingU.S. patent application Ser. Nos. (08/756,501) and (08/753,505),referred to herein. Such organic nitrogen compounds may be used to reactwith and to neutralize the acidic compounds by forming conversionproduct salts therewith, thereby preventing the rhodium from complexingwith the acidic hydrolysis byproducts and thus helping to protect theactivity of the metal, e.g., rhodium, catalyst while it is present inthe reaction zone under hydroformylation conditions. The choice of theorganic nitrogen compound for this function is, in part, dictated by thedesirability of using a basic material that is soluble in the reactionmedium and does not tend to catalyze the formation of aldols and othercondensation products at a significant rate or to unduly react with theproduct aldehyde.

Such organic nitrogen compounds may contain from 2 to 30 carbon atoms,and preferably from 2 to 24 carbon atoms. Primary amines should beexcluded from use as said organic nitrogen compounds. Preferred organicnitrogen compounds should have a distribution coefficient that favorssolubility in the organic phase. In general more preferred organicnitrogen compounds useful for scavenging the phosphorus acidic compoundspresent in the hydroformylation reaction product fluid of this inventioninclude those having a pKa value within ±3 of the pH of the aqueousbuffer solution employed. Most preferably the pKa value of the organicnitrogen compound will be essentially about the same as the pH of theaqueous buffer solution employed. Of course it is to be understood thatwhile it may be preferred to employ only one such organic nitrogencompound at a time in any given hydroformylation process, if desired,mixtures of two or more different organic nitrogen compounds may also beemployed in any given processes.

Illustrative organic nitrogen compounds include e.g., trialkylamines,such as triethylamine, tri-n-propylamine, tri-n-butylamine,tri-iso-butylamine, tri-iso-propylamine, tri-n-hexylamine,tri-n-octylamine, dimethyl-iso-propylamine, dimethyl-hexadecylamine,methyl-di-n-octylamine, and the like, as well as substituted derivativesthereof containing one or more noninterfering substituents such ashydroxy groups, for example triethanolamine, N-methyl-di-ethanolamine,tris-(3-hydroxypropyl)-amine, and the like. Heterocyclic amines can alsobe used such as pyridine, picolines, lutidines, collidines,N-methylpiperidine, N-methylmorpholine, N-2'-hydroxyethylmorpholine,quinoline, iso-quinoline, quinoxaline, acridien, quinuclidine, as wellas, diazoles, triazole, diazine and triazine compounds, and the like.Also suitable for possible use are aromatic tertiary amines, such asN,N-dimethylaniline, N,N-diethylaniline, N,N-dimethyl-p-toluidine,N-methyldiphenylamine, N,N-dimethylbenzylamine,N,N-dimethyl-1-naphthylamine, and the like. Compounds containing two ormore amino groups, such as N,N,N',N'-tetramethylethylene diamine andtriethylene diamine (i.e. 1,4-diazabicyclo- 2,2,2!-octane) can also bementioned.

Preferred organic nitrogen compounds useful for scavenging thephosphorus acidic compounds present in the hydroformylation reactionproduct fluids of the this invention are heterocyclic compounds selectedfrom the group consisting of diazoles, triazoles, diazines andtriazines, such as those disclosed and employed herein. For example,benzimidazole and benztriazole are preferred candidates for such use.

Illustrative of suitable organic nitrogen compounds useful forscavenging the phosphorus acidic compounds include those permissibleorganic nitrogen compounds described in Kirk-Othmer, Encyclopedia ofChemical Technology, Fourth Edition, 1996, the pertinent portions ofwhich are incorporated herein by reference.

The amount of organic nitrogen compound that may be present in thereaction product fluid for scavenging the phosphorus acidic compoundspresent in the hydroformylation reaction product fluids of the thisinvention is typically sufficient to provide a concentration of at leastabout 0.0001 moles of free organic nitrogen compound per liter ofreaction product fluid. In general the ratio of organic nitrogencompound to total organophosphite ligand (whether bound with rhodium orpresent as free organophosphite) is at least about 0.1:1 and even morepreferably at least about 0.5:1. The upper limit on the amount oforganic nitrogen compound employed is governed mainly by economicalconsiderations. Organic nitrogen compound: organophosphite molar ratiosof at least about 1:1 up to about 5:1 should be sufficient for mostpurpose.

It is to be understood the organic nitrogen compound employed toscavenge said phosphorus acidic compounds need not be the same as theheterocyclic nitrogen compound employed to protect the metal catalystunder harsh conditions such as exist in the aldehydevaporizer-separator. However, if said organic nitrogen compound and saidheterocyclic nitrogen compound are desired to be the same and performboth said functions in a given process, care should be taken to see thatthere will be a sufficient amount of the heterocyclic nitrogen compoundpresent in the reaction medium to also provide that amount of freeheterocyclic nitrogen compound in the hydroformylation process, e.g.,vaporizer-separator, that will allow both desired functions to beachieved.

Accordingly the aqueous buffer solution treatment of this invention willnot only remove free phosphoric acidic compounds from themetal-organophosphite ligand complex catalyst containing reactionproduct fluids, the aqueous buffer solution also surprisingly removesthe phosphorus acidic material of the conversion product salt formed bythe use of the organic nitrogen compound scavenger when employed, i.e.,the phosphorus acid of said conversion product salt remains behind inthe aqueous buffer solution, while the treated reaction product fluid,along with the reactivated (free) organic nitrogen compound is returnedto the hydroformylation reaction zone.

An alternate method of transferring acidity from the hydroformylationreaction product fluid to an aqueous fraction is through theintermediate use of a heterocyclic amine which has a fluorocarbon orsilicone side chain of sufficient size that it is immiscible in both thehydroformylation reaction product fluid and in the aqueous fraction. Theheterocyclic amine may first be contacted with the hydroformylationreaction product fluid where the acidity present in the reaction productfluid will be transferred to the nitrogen of the heterocyclic amine.This heterocyclic amine layer may then be decanted or otherwiseseparated from the reaction product fluid before contacting it with theaqueous fraction where it again would exist as a separate phase. Theheterocyclic amine layer may then be returned to contact thehydroformylation reaction product fluid.

Another means for preventing or minimizing ligand degradation andcatalyst deactivation and/or precipitation that may be useful in thisinvention involves carrying out the invention described and taught incopending U.S. patent application Ser. Nos. (08/753,504) and(08/753,503), both filed on an even date herewith, the disclosures ofwhich are incorporated herein by reference, which comprises using waterand optionally organic nitrogen compounds as disclosed therein.

For instance, it has been found that hydrolytic decomposition andrhodium catalyst deactivation as discussed herein can be prevented orlessened by treating at least a portion of the reaction product fluidderived from the hydroformylation process and which also containsphosphorus acidic compounds formed during the hydroformylation processwith water sufficient to remove at least some amount of the phosphorusacidic compounds from the reaction product fluid. Although both waterand acid are factors in the hydrolysis of organophosphite ligands, ithas been surprisingly discovered that hydroformylation reaction systemsare more tolerant of higher levels of water than higher levels of acid.Thus, the water can surprisingly be used to remove acid and decrease therate of loss of organophosphite ligand by hydrolysis.

Yet another means for preventing or minimizing ligand degradation andcatalyst deactivation and/or precipitation that may be useful in thisinvention involves carrying out the invention described and taught incopending U.S. patent application Ser. Nos. (08/757,742) and(08/756,786), both filed on an even date herewith, the disclosures ofwhich are incorporated herein by reference, which comprises using waterin conjunction with acid removal substances and optionally organicnitrogen compounds as disclosed therein.

For instance, it has been found that hydrolytic decomposition andrhodium catalyst deactivation as discussed herein can be prevented orlessened by treating at least a portion of the reaction product fluidderived from the hydroformylation process and which also containsphosphorus acidic compounds formed during said hydroformylation processwith water in conjunction with one or more acid removal substances,e.g., oxides, hydroxides, carbonates, bicarbonates and carboxylates ofGroup 2, 11 and 12 metals, sufficient to remove at least some amount ofthe phosphorus acidic compounds from said reaction product fluid.Because metal salt contaminants, e.g., iron, zinc, calcium salts and thelike, in a hydroformylation reaction product fluid undesirably promotethe self condensation of aldehydes, an advantage is that one can use theacidity removing capability of certain acid removal substances withminimal transfer of metal salts to the hydroformylation reaction productfluid.

A further means for preventing or minimizing ligand degradation andcatalyst deactivation and/or precipitation that may be useful in thisinvention involves carrying out the invention described and taught incopending U.S. patent application Ser. Nos. (08/756,482) and(08/756,788), both filed on an even date herewith, the disclosures ofwhich are incorporated herein by reference, which comprises using ionexchange resins and optionally organic nitrogen compounds as disclosedtherein.

For instance, it has been found that hydrolytic decomposition andrhodium catalyst deactivation as discussed herein can be prevented orlessened by (a) treating in at least one scrubber zone at least aportion of said reaction product fluid derived from saidhydroformylation process and which also contains phosphorus acidiccompounds formed during said hydroformylation process with watersufficient to remove at least some amount of the phosphorus acidiccompounds from said reaction product fluid and (b) treating in at leastone ion exchange zone at least a portion of the water which containsphosphorus acidic compounds removed from said reaction product fluidwith one or more ion exchange resins sufficient to remove at least someamount of the phosphorus acidic compounds from said water. Becausepassing a hydroformylation reaction product fluid directly through anion exchange resin can cause rhodium precipitation on the ion exchangeresin surface and pores, thereby causing process complications, anadvantage is that one can use the acidity removing capability of ionexchange resins with essentially no loss of rhodium.

Other means for removing phosphorus acidic compounds from the reactionproduct fluids of this invention may be employed if desired. Thisinvention is not intended to be limited in any manner by the permissiblemeans for removing phosphorus acidic compounds from the reaction productfluids.

Another problem that has been observed when organopolyphosphite ligandpromoted metal catalysts are employed in hydroformylation processes,e.g., continuous liquid catalyst recycle hydroformylation processes,that involve harsh conditions such as recovery of the aldehyde via avaporizer-separator, i.e. the slow loss in catalytic activity of thecatalysts is believed due at least in part to the harsh conditions suchas exist in a vaporizer employed in the separation and recovery of thealdehyde product from its reaction product fluid. For instance, it hasbeen found that when an organopolyphosphite promoted rhodium catalyst isplaced under harsh conditions such as high temperature and low carbonmonoxide partial pressure, that the catalyst deactivates at anaccelerated pace with time, due most likely to the formation of aninactive or less active rhodium species, which may also be susceptibleto precipitation under prolonged exposure to such harsh conditions. Suchevidence is also consistent with the view that the active catalyst whichunder hydroformylation conditions is believed to comprise a complex ofrhodium, organopolyphosphite, carbon monoxide and hydrogen, loses atleast some of its coordinated carbon monoxide ligand during exposure tosuch harsh conditions as encountered in vaporization, which provides aroute for the formation of catalytically inactive or less active rhodiumspecies. The means for preventing or minimizing such catalystdeactivation and/or precipitation involves carrying out the inventiondescribed and taught in copending U.S. patent application Ser. No.(08/756,789), filed on an even date herewith, the disclosure of which isincorporated herein by reference, which comprises carrying out thehydroformylation process under conditions of low carbon monoxide partialpressure in the presence of a free heterocyclic nitrogen compound asdisclosed therein.

By way of further explanation it is believed the free heterocyclicnitrogen compound serves as a replacement ligand for the lost carbonmonoxide ligand thereby forming a neutral intermediate metal speciescomprising a complex of the metal, organopolyphosphite, the heterocyclicnitrogen compound and hydrogen during such harsh conditions, e.g.,vaporization separation, thereby preventing or minimizing the formationof any such above mentioned catalytic inactive or less active metalspecies. It is further theorized that the maintenance of catalyticactivity, or the minimization of its deactivation, throughout the courseof such continuous liquid recycle hydroformylation is due toregeneration of the active catalyst from said neutral intermediate metalspecies in the reactor (i.e. hydroformylation reaction zone) of theparticular hydroformylation process involved. It is believed that underthe higher syn gas pressure hydroformylation conditions in the reactor,the active catalyst complex comprising metal, e.g., rhodium,organopolyphosphite, carbon monoxide and hydrogen is regenerated as aresult of some of the carbon monoxide in the reactant syn gas replacingthe heterocyclic nitrogen ligand of the recycled neutral intermediaterhodium species. That is to say, carbon monoxide having a strongerligand affinity for rhodium, replaces the more weakly bondedheterocyclic nitrogen ligand of the recycled neutral intermediaterhodium species that was formed during vaporization separation asmentioned above, thereby reforming the active catalyst in thehydroformylation reaction zone.

Thus the possibility of metal catalyst deactivation due to such harshconditions is said to be minimized or prevented by carrying out suchdistillation of the desired aldehyde product from themetal-organopolyphosphite catalyst containing product fluids in theadded presence of a free heterocyclic nitrogen compound having a five orsix membered heterocyclic ring consisting of 2 to 5 carbon atoms andfrom 2 to 3 nitrogen atoms, at least one of said nitrogen atomscontaining a double bond. Such free heterocyclic nitrogen compounds maybe selected from the class consisting of diazole, triazole, diazine, andtriazine compounds, such as, e.g., benzimidazole or benzotriazole, andthe like. The term "free" as it applies to said heterocyclic nitrogencompounds is employed therein to exclude any acid salts of suchheterocyclic nitrogen compounds, i.e., salt compounds formed by thereaction of any phosphorus acidic compound present in thehydroformylation reaction medium with such free heterocyclic nitrogencompounds as discussed herein above.

It is to be understood that while it may be preferred to employ only onefree heterocyclic nitrogen compound at a time in any givenhydroformylation process, if desired, mixtures of two or more differentfree heterocyclic nitrogen compounds may also be employed in any givenprocess. Moreover the amount of such free heterocyclic nitrogencompounds present during harsh conditions, e.g., the vaporizationprocedure, need only be that minimum amount necessary to furnish thebasis for at least some minimization of such catalyst deactivation asmight be found to occur as a result of carrying out an identical metalcatalyzed liquid recycle hydroformylation process under essentially thesame conditions, in the absence of any free heterocyclic nitrogencompound during vaporization separation of the aldehyde product. Amountsof such free heterocyclic nitrogen compounds ranging from about 0.01 upto about 10 weight percent, or higher if desired, based on the totalweight of the hydroformylation reaction product fluid to be distilledshould be sufficient for most purposes.

In addition to hydroformylation processes, other processes for whichthis invention may be useful include those which exhibit a loss incatalytic activity of organopolyphosphite promoted metal catalysts dueto harsh reaction conditions such as employed in the separation andrecovery of product from its reaction product fluid. Illustrativeprocesses include, for example, hydroacylation (intramolecular andintermolecular), hydroamidation, hydroesterification, aminolysis,alcoholysis, carbonylation, olefin isomerization, transfer hydrogenationand the like. Preferred processes involve the reaction of organiccompounds with carbon monoxide, or with carbon monoxide and a thirdreactant, e.g., hydrogen, or with hydrogen cyanide, in the presence of acatalytic amount of a metal-organopolyphosphite ligand complex catalyst.The most preferred processes include hydroformylation and carbonylation.

As with hydroformylation processes, these other processes may beasymmetric or non-asymmetric, the preferred processes beingnon-asymmetric, and may be conducted in any continuous orsemi-continuous fashion and may involve any catalyst liquid and/or gasrecycle operation desired. The particular processes for producingproducts from one or more reactants, as well as the reaction conditionsand ingredients of the processes are not critical features of thisinvention. The processing techniques of this invention may correspond toany of the known processing techniques heretofore employed inconventional processes. For instance, the processes can be conducted ineither the liquid or gaseous states and in a continuous, semi-continuousor batch fashion and involve a liquid recycle and/or gas recycleoperation or a combination of such systems as desired. Likewise, themanner or order of addition of the reaction ingredients, catalyst andsolvent are also not critical and may be accomplished in anyconventional fashion. This invention encompasses the carrying out ofknown conventional syntheses in a conventional fashion employing ametal-organophosphite ligand complex catalyst.

The hydroformylation processes of this invention may be carried outusing, for example, a fixed bed reactor, a fluid bed reactor, acontinuous stirred tank reactor (CSTR), or a slurry reactor. The optimumsize and shape of the catalysts will depend on the type of reactor used.In general, for fluid bed reactors, a small, spherical catalyst particleis preferred for easy fluidization. With fixed bed reactors, largercatalyst particles are preferred so the back pressure within the reactoris kept reasonably low. The at least one reaction zone employed in thisinvention may be a single vessel or may comprise two or more discretevessels. The at least one separation zone employed in this invention maybe a single vessel or may comprise two or more discrete vessels. The atleast one scrubber zone employed in this invention may be a singlevessel or may comprise two or more discreet vessels. It should beunderstood that the reaction zone(s) and separation zone(s) employedherein may exist in the same vessel or in different vessels. Forexample, reactive separation techniques such as reactive distillation,reactive membrane separation and the like may occur in the reactionzone(s).

The hydroformylation processes of this invention can be conducted in abatch or continuous fashion, with recycle of unconsumed startingmaterials if required. The reaction can be conducted in a singlereaction zone or in a plurality of reaction zones, in series or inparallel or it may be conducted batchwise or continuously in anelongated tubular zone or series of such zones. The materials ofconstruction employed should be inert to the starting materials duringthe reaction and the fabrication of the equipment should be able towithstand the reaction temperatures and pressures. Means to introduceand/or adjust the quantity of starting materials or ingredientsintroduced batchwise or continuously into the reaction zone during thecourse of the reaction can be conveniently utilized in the processesespecially to maintain the desired molar ratio of the startingmaterials. The reaction steps may be effected by the incrementaladdition of one of the starting materials to the other. Also, thereaction steps can be combined by the joint addition of the startingmaterials. When complete conversion is not desired or not obtainable,the starting materials can be separated from the product, for example bydistillation, and the starting materials then recycled back into thereaction zone.

The hydroformylation processes may be conducted in either glass lined,stainless steel or similar type reaction equipment. The reaction zonemay be fitted with one or more internal and/or external heatexchanger(s) in order to control undue temperature fluctuations, or toprevent any possible "runaway" reaction temperatures.

The hydroformylation processes of this invention may be conducted in oneor more steps or stages. The exact number of reaction steps or stageswill be governed by the best compromise between capital costs andachieving high catalyst selectivity, activity, lifetime and ease ofoperability, as well as the intrinsic reactivity of the startingmaterials in question and the stability of the starting materials andthe desired reaction product to the reaction conditions.

In an embodiment, the hydroformylation processes useful in thisinvention may be carried out in a multistaged reactor such as described,for example, in copending U.S. patent application Ser. No. (08/757,743),filed on an even date herewith, the disclosure of which is incorporatedherein by reference. Such multistaged reactors can be designed withinternal, physical barriers that create more than one theoreticalreactive stage per vessel. In effect, it is like having a number ofreactors inside a single continuous stirred tank reactor vessel.Multiple reactive stages within a single vessel is a cost effective wayof using the reactor vessel volume. It significantly reduces the numberof vessels that otherwise would be required to achieve the same results.Fewer vessels reduces the overall capital required and maintenanceconcerns with separate vessels and agitators.

For purposes of this invention, the term "hydrocarbon" is contemplatedto include all permissible compounds having at least one hydrogen andone carbon atom. Such permissible compounds may also have one or moreheteroatoms. In a broad aspect, the permissible hydrocarbons includeacyclic (with or without heteroatoms) and cyclic, branched andunbranched, carbocyclic and heterocyclic, aromatic and nonaromaticorganic compounds which can be substituted or unsubstituted.

As used herein, the term "substituted" is contemplated to include allpermissible substituents of organic compounds unless otherwiseindicated. In a broad aspect, the permissible substituents includeacyclic and cyclic, branched and unbranched, carbocyclic andheterocyclic, aromatic and nonaromatic substituents of organiccompounds. Illustrative substituents include, for example, alkyl,alkyloxy, aryl, aryloxy, hydroxy, hydroxyalkyl, amino, aminoalkyl,halogen and the like in which the number of carbons can range from 1 toabout 20 or more, preferably from 1 to about 12. The permissiblesubstituents can be one or more and the same or different forappropriate organic compounds. This invention is not intended to belimited in any manner by the permissible substituents of organiccompounds.

Certain of the following examples are provided to further illustratethis invention.

EXAMPLE 1

A system utilizing rhodium and Ligand F (as identified herein) as thecatalyst is used to hydroformylate propylene to butyraldehyde. Theconcentration of the ligand is 2 weight percent at all rhodiumconcentrations given in Table A below. The system operates in acontinuously stirred tank reactor. Catalyst dissolved in butyraldehydeand hydroformylation byproducts is fed to the reactor to maintain thecatalyst concentration in the reactor at a rate of 140 grams per hourper liter of volume available for reaction. The ability of the catalystto react feeds is represented by a factor that is dependent on thetemperature and rhodium metal concentration in the reactor. Table Agives examples for the value of the factor at various conditions atwhich the catalyst system is operated. The difference in temperaturebetween the reaction and the inlet temperature of the fluid to the heattransfer means to prevent cycling will be the same for comparable valuesof the relative reactivity constant. The pressure of the reaction systemis 250 psia. Propylene is fed to the reactor along as well as synthesisgas to provide the reactants necessary for the hydroformylationreaction. Inerts in the feeds amount to less than 5 weight percent ofthe total weight of the feeds. Excess gases exit the reactor from avapor purge line. Reaction product fluid is continuously removed fromthe reactor at a rate that maintains the liquid level within thereactor. Several examples are given for the temperature differencesbetween the reaction and the inlet of the coolant to the heat transfermeans that prevent the system from undergoing extreme cycling during theoperation of the reactor system. The feed rate of the olefin to thesystem is 224.4 grams per hour per liter of reaction volume. Table Bsummarizes results for several different feed compositions fortemperature differences between the reaction and the temperature of thecoolant entering the heat transfer means that prevent the system fromundergoing extreme cycling.

                  TABLE A                                                         ______________________________________                                        Factor for the Reactivity of Ligand F at Various Conditions                          Temperatures, deg C.                                                   Rh, ppm  25        45     60      100  120                                    ______________________________________                                         10      0.01      0.03   0.08    0.53 1.19                                    30      0.03      0.10   0.24    1.59 3.57                                    60      0.06      0.20   0.47    3.18 7.14                                   100      0.10      0.34   0.78    5.30 11.90                                  150      0.15      0.51   1.18    7.94 17.84                                  200      0.19      0.68   1.57    10.59                                                                              23.79                                  250      0.24      0.85   1.96    13.24                                                                              29.74                                  300      0.29      1.02   2.35    15.89                                                                              35.69                                  ______________________________________                                    

                  TABLE B                                                         ______________________________________                                        Summary of Temperature Differences to Eliminate Cycling                       Reactiv                                                                             Propylene            Hydrogen to                                                                             Temperature                              ity   Conversion,                                                                             Syn Gas Feed,                                                                            Carbon    Difference,                              Factor                                                                              %         g/hr/L     Monoxide Ratio                                                                          deg C.                                   ______________________________________                                        2.6   75        171        1:1        7                                       1.13  60        133        0.85      13                                       1.40  65        138        0.85      24                                       ______________________________________                                    

EXAMPLE 2

A system utilizing rhodium and Ligand F (as identified herein) as thecatalyst is used to hydroformylate propylene to butyraldehyde. Theconcentration of the ligand is 2 weight percent at all rhodiumconcentrations given in Table C below. The system operates in acontinuously stirred tank reactor. Catalyst dissolved in butyraldehydeand hydroformylation by-products is fed at a rate of 140 grams per hourper liter of volume available for reaction to the reactor to maintainthe catalyst concentration in the reactor. The ability of the catalystto react feeds is represented by a factor that is dependent on thetemperature and rhodium metal concentration in the reactor. Table Cgives examples for the value of the factor at various conditions atwhich the catalyst system is operated. The conversions and temperaturedifference between the reaction and the inlet coolant to the heattransfer means to prevent cycling in the system will be the same forcomparable values of the relative reactivity constant. The pressure ofthe reaction system is 250 psia. Propylene is fed to the reactor alongas well as synthesis gas to provide the reactants necessary for thehydroformylation reaction. Inert compounds in the feeds amount to lessthan 5 weight percent of the total weight of the feeds. Excess gasesexit the reactor from a vapor purge line. Reaction product fluid iscontinuously removed from the reactor at a rate that maintains theliquid level within the reactor. Several examples are given for theoperating conditions that prevent the system from undergoing extremecycling during the operation of the reactor system. The feed rate of theolefin to the system is 224.4 grams per hour per liter of reactionvolume. Table D summarizes results for several different feedcompositions along with the temperature difference between the reactionand the temperature of the coolant entering the heat transfer means andconversions of different reactants that prevent the system fromundergoing extreme cycling.

                  TABLE C                                                         ______________________________________                                        Factor for the Reactivity of Ligand F at Various Conditions                          Temperatures, deg C.                                                   Rh, ppm  25        45     60      100  120                                    ______________________________________                                         10      0.01      0.03   0.08    0.53 1.19                                    30      0.03      0.10   0.24    1.59 3.57                                    60      0.06      0.20   0.47    3.18 7.14                                   100      0.10      0.34   0.78    5.30 11.90                                  150      0.15      0.51   1.18    7.94 17.84                                  200      0.19      0.68   1.57    10.59                                                                              23.79                                  250      0.24      0.85   1.96    13.24                                                                              29.74                                  300      0.29      1.02   2.35    15.89                                                                              35.69                                  ______________________________________                                    

                                      TABLE D                                     __________________________________________________________________________    Summary of Results to Eliminate Cycling                                                                      Hydrogen                                                                      to Carbon                                      Temperature        Carbon Syn Gas                                                                            Monoxide                                       Difference,                                                                         Propylene                                                                            Hydrogen                                                                            Monoxide                                                                             Feed Rate,                                                                         Ratio in                                       Deg C.                                                                              Conversion                                                                           Conversion                                                                          Conversion                                                                           g/hr/L                                                                             Feed                                           __________________________________________________________________________    36    60     96    87     117  0.90                                           18    60     69    59     171  0.85                                           17    60     60    60     171  1.00                                           __________________________________________________________________________

Examples 3 to 7 illustrate the in situ buffering effect of nitrogencontaining additives such as benzimidazole and the ability of theseadditives to transfer the acidity to an aqueous buffer solution.

EXAMPLE 3

This control example illustrates the stability of Ligand D (asidentified herein) in a solution containing 200 parts per million ofrhodium, and 0.39 percent by weight of Ligand D in butyraldehydecontaining aldehyde dimer and trimer in the absence of added acid orbenzimidazole.

To a clean, dry 25 milliliter vial was added 12 grams of thebutyraldehyde solution mentioned above. Samples were analyzed for LigandD using High Performance Liquid Chromatography after 24 and 72 hours.The weight percent of Ligand D was determined by High Performance LiquidChromatography relative to a calibration curve. No change in theconcentration of Ligand D was observed after either 24 or 72 hours.

EXAMPLE 4

This Example is similar to Example 3 except that phosphorus acid wasadded to simulate the type of acid that might be formed duringhydrolysis of an organophosphite.

The procedure for Example 3 was repeated with the modification of adding0.017 grams of phosphorous acid (H₃ PO₃) to the 12 gram solution. After24 hours the concentration of Ligand D had decreased from 0.39 to 0.12percent by weight; after 72 hours the concentration of Ligand D haddecreased to 0.04 percent by weight. This data shows that strong acidscatalyze the decomposition of Ligand D.

EXAMPLE 5

This Example is similar to Example 3 except that both phosphorus acidand benzimidazole were added.

The procedure for Example 3 was repeated with the modification of adding0.018 grams of phosphorous acid and 0.0337 grams of benzimidazole to thesolution. No decomposition of Ligand D was observed after either 24 or72 hours. This shows that the addition of benzimidazole effectivelybuffers the effect of the strong acid and thereby prevents the rapiddecomposition of Ligand D.

EXAMPLE 6

This example shows that an aqueous buffer can recover the acidity fromthe nitrogen base in situ buffer and allow the nitrogen base topartition into the organic phase, where it can be recycled to thehydroformylation zone.

Solid (benzimidazole)(H₃ PO₄) was prepared by placing 1.18 grams (10mmole) of benzimidazole in a 250 milliliter beaker and dissolving thebenzimidazole in 30 milliliters of tetrahydrofuran. To this solution wasslowly added 0.5 grams of 86 percent by weight of phosphoric acid (H₃PO₄). Upon addition of the acid a precipitate formed. The precipitatewas collected on a sintered glass frit and washed with tetrahydrofuran.The resulting solid was air-dried with the application of vacuum andused without any further purification. 0.109 grams (0.504 mmole) of thewater-soluble (benzimidazole)(H₃ PO₄) solid prepared in the previousstep was dissolved in 10 grams of 0.1M pH 7 sodium phosphate buffersolution. The resulting solution was extracted with 10 grams ofvaleraldehyde. The organic layer was then separated from the aqueouslayer using a separatory funnel. The volatile components were thenremoved from the organic layer by distillation at 100° C. to yield asolid. The solid was identical to authentic benzimidazole as shown bythin layer chromatography utilizing a 1:1 by volume mixture ofchloroform and acetone as the eluent and silica as the stationary phase.Based on recovery of the solid, benzimidazole was completely transferredto the organic phase.

This data shows that an organic soluble nitrogen base which exists as astrong acid salt can be regenerated by contact with an aqueous bufferand returned to the organic phase.

EXAMPLE 7

This example shows that a buffer solution is effective at neutralizingan organic soluble salt of a weak base and strong acid thus allowing thebase to return to the organic phase and effectively removing the acidfrom the organic phase.

A butyraldehyde solution was prepared containing 1.0 percent by weightof benzotriazole. The solution was then analyzed by Gas Chromatographyfor benzotriazole content to serve as a reference sample. To thesolution prepared in the previous step was added 0.25 mole equivalentsof phosphorous acid (H₃ PO₃). In a one pint glass bottle was added 50grams of the butyraldehyde solution containing benzotriazole and 50grams of a pH 7, 0.2 molar sodium phosphate buffer solution. The mixturewas stirred for 15 minutes and then transferred to a separatory funnel.The aqueous layer was then separated from the aldehyde layer. Theaqueous layer was analyzed for H₃ PO₃ content by Ion Chromatography. Thealdehyde layer was analyzed for benzotriazole content by GasChromatography and H₃ PO₃ content by Ion Chromatography. The H₃ PO₃ wasfound to be completely transferred into the aqueous layer. Completereturn of benzotriazole to the butyraldehyde layer was also found.

This data shows that an organic soluble salt of a weak base and strongacid can be completely neutralized by contacting the organic phase withan aqueous buffer solution and that the free base is thereby returned tothe organic phase.

Although the invention has been illustrated by certain of the precedingexamples, it is not to be construed as being limited thereby; butrather, the invention encompasses the generic area as hereinbeforedisclosed. Various modifications and embodiments can be made withoutdeparting from the spirit and scope thereof.

We claim:
 1. A process which comprises reacting one or more reactants inthe presence of a metal-organopolyphosphite ligand complex catalyst andoptionally free organopolyphosphite ligand to produce a reaction productfluid comprising one or more products, wherein said process is conductedat a carbon monoxide partial pressure such that reaction rate increasesas carbon monoxide partial pressure decreases and reaction ratedecreases as carbon monoxide partial pressure increases and which issufficient to prevent and/or lessen deactivation of themetal-organopolyphosphite ligand complex catalyst.
 2. A hydroformylationprocess which comprises reacting one or more olefinic unsaturatedcompounds with carbon monoxide and hydrogen in the presence of ametal-organopolyphosphite ligand complex catalyst and optionally freeorganopolyphosphite ligand to produce a reaction product fluidcomprising one or more aldehydes, wherein said hydroformylation processis conducted at a carbon monoxide partial pressure such thathydroformylation reaction rate increases as carbon monoxide partialpressure decreases and hydroformylation reaction rate decreases ascarbon monoxide partial pressure increases and which is sufficient toprevent and/or lessen deactivation of the metal-organopolyphosphiteligand complex catalyst and at one or more of the following conditions:(a) at a temperature such that the temperature difference betweenreaction product fluid temperature and inlet coolant temperature issufficient to prevent and/or lessen cycling of carbon monoxide partialpressure, hydrogen partial pressure, total reaction pressure,hydroformylation reaction rate and/or temperature during saidhydroformylation process, (b) at a carbon monoxide conversion sufficientto prevent and/or lessen cycling of carbon monoxide partial pressure,hydrogen partial pressure, total reaction pressure, hydroformylationreaction rate and/or temperature during said hydroformylation process,(c) at a hydrogen conversion sufficient to prevent and/or lessen cyclingof carbon monoxide partial pressure, hydrogen partial pressure, totalreaction pressure, hydroformylation reaction rate and/or temperatureduring said hydroformylation process, and (d) at an olefinic unsaturatedcompound conversion sufficient to prevent and/or lessen cycling ofcarbon monoxide partial pressure, hydrogen partial pressure, totalreaction pressure, hydroformylation reaction rate and/or temperatureduring said hydroformylation process.
 3. The hydroformylation process ofclaim 2 which comprises reacting one or more olefinic unsaturatedcompounds with carbon monoxide and hydrogen in the presence of ametal-organopolyphosphite ligand complex catalyst and optionally freeorganopolyphosphite ligand to produce a reaction product fluidcomprising one or more aldehydes, wherein said hydroformylation processis conducted at a carbon monoxide partial pressure such thathydroformylation reaction rate increases as carbon monoxide partialpressure decreases and hydroformylation reaction rate decreases ascarbon monoxide partial pressure increases and which is sufficient toprevent and/or lessen deactivation of the metal-organopolyphosphiteligand complex catalyst, and at a temperature such that the temperaturedifference between reaction product fluid temperature and inlet coolanttemperature is sufficient to prevent and/or lessen cycling of carbonmonoxide partial pressure, hydrogen partial pressure, total reactionpressure, hydroformylation reaction rate and/or temperature during saidhydroformylation process, and at one or more of the followingconditions: (a) at a carbon monoxide conversion sufficient to preventand/or lessen cycling of carbon monoxide partial pressure, hydrogenpartial pressure, total reaction pressure, hydroformylation reactionrate and/or temperature during said hydroformylation process, (b) at ahydrogen conversion sufficient to prevent and/or lessen cycling ofcarbon monoxide partial pressure, hydrogen partial pressure, totalreaction pressure, hydroformylation reaction rate and/or temperatureduring said hydroformylation process, and (c) at an olefinic unsaturatedcompound conversion sufficient to prevent and/or lessen cycling ofcarbon monoxide partial pressure, hydrogen partial pressure, totalreaction pressure, hydroformylation reaction rate and/or temperatureduring said hydroformylation process.
 4. An improved hydroformylationprocess which comprises (i) reacting in at least one reaction zone oneor more olefinic unsaturated compounds with carbon monoxide and hydrogenin the presence of a metal-organopolyphosphite ligand complex catalystand optionally free organopolyphosphite ligand to produce a reactionproduct fluid comprising one or more aldehydes and (ii) separating in atleast one separation zone or in said at least one reaction zone the oneor more aldehydes from said reaction product fluid, the improvementcomprising preventing and/or lessening deactivation of themetal-organopolyphosphite ligand complex catalyst and preventing and/orlessening cycling of carbon monoxide partial pressure, hydrogen partialpressure, total reaction pressure, hydroformylation reaction rate and/ortemperature during said hydroformylation process by conducting saidhydroformylation process at a carbon monoxide partial pressure such thathydroformylation reaction rate increases as carbon monoxide partialpressure decreases and hydroformylation reaction rate decreases ascarbon monoxide partial pressure increases and at one or more of thefollowing conditions: (a) at a temperature such that the temperaturedifference between reaction product fluid temperature and inlet coolanttemperature is less than about 25° C., (b) at a carbon monoxideconversion of less than about 90%, (c) at a hydrogen conversion ofgreater than about 65%, and (d) at an olefinic unsaturated compoundconversion of greater than about 50%.
 5. A hydroformylation processwhich comprises reacting one or more olefinic unsaturated compounds withcarbon monoxide and hydrogen in the presence of ametal-organopolyphosphite ligand complex catalyst and optionally freeorganopolyphosphite ligand to produce a reaction product fluidcomprising one or more aldehydes, wherein said hydroformylation processis conducted at a carbon monoxide partial pressure such thathydroformylation reaction rate increases as carbon monoxide partialpressure decreases and hydroformylation reaction rate decreases ascarbon monoxide partial pressure increases and which is sufficient toprevent and/or lessen deactivation of the metal-organopolyphosphiteligand complex catalyst.
 6. An improved hydroformylation process whichcomprises (i) reacting in at least one reaction zone one or moreolefinic unsaturated compounds with carbon monoxide and hydrogen in thepresence of a metal-organopolyphosphite ligand complex catalyst andoptionally free organopolyphosphite ligand to produce a reaction productfluid comprising one or more aldehydes and (ii) separating in at leastone separation zone or in said at least one reaction zone the one ormore aldehydes from said reaction product fluid, wherein said reactionproduct fluid contains at least some organomonophosphite ligand formedduring said hydroformylation process, the improvement comprisingconducting said hydroformylation process at a carbon monoxide partialpressure such that hydroformylation reaction rate increases as carbonmonoxide partial pressure decreases and hydroformylation reaction ratedecreases as carbon monoxide partial pressure increases and which issufficient to prevent and/or lessen coordination of theorganomonophosphite ligand with said metal-organopolyphosphite ligandcomplex catalyst and at one or more of the following conditions: (a) ata temperature such that the temperature difference between reactionproduct fluid temperature and inlet coolant temperature is sufficient toprevent and/or lessen cycling of carbon monoxide partial pressure,hydrogen partial pressure, hydroformylation reaction rate and/ortemperature during said hydroformylation process, (b) at a carbonmonoxide conversion sufficient to prevent and/or lessen cycling ofcarbon monoxide partial pressure, hydrogen partial pressure,hydroformylation reaction rate and/or temperature during saidhydroformylation process, (c) at a hydrogen conversion sufficient toprevent and/or lessen cycling of carbon monoxide partial pressure,hydrogen partial pressure, hydroformylation reaction rate and/ortemperature during said hydroformylation process, and (d) at an olefinicunsaturated compound conversion sufficient to prevent and/or lessencycling of carbon monoxide partial pressure, hydrogen partial pressure,hydroformylation reaction rate and/or temperature during saidhydroformylation process.
 7. The improved hydroformylation process ofclaim 6 which comprises (i) reacting in at least one reaction zone oneor more olefinic unsaturated compounds with carbon monoxide and hydrogenin the presence of a metal-organopolyphosphite ligand complex catalystand optionally free organopolyphosphite ligand to produce a reactionproduct fluid comprising one or more aldehydes and (ii) separating in atleast one separation zone or in said at least one reaction zone the oneor more aldehydes from said reaction product fluid, wherein saidreaction product fluid contains at least some organomonophosphite ligandformed during said hydroformylation process, the improvement comprisingpreventing and/or lessening coordination of the organomonophosphiteligand with said metal-organopolyphosphite ligand complex catalyst andpreventing and/or lessening cycling of carbon monoxide partial pressure,hydrogen partial pressure, total reaction pressure, hydroformylationreaction rate and/or temperature during said hydroformylation process byconducting said hydroformylation process at a carbon monoxide partialpressure such that hydroformylation reaction rate increases as carbonmonoxide partial pressure decreases and hydroformylation reaction ratedecreases as carbon monoxide partial pressure increases and at one ormore of the following conditions: (a) at a temperature such that thetemperature difference between reaction product fluid temperature andinlet coolant temperature is less than about 25° C., (b) at a carbonmonoxide conversion of less than about 90%, (c) at a hydrogen conversionof greater than about 65%, and (d) at an olefinic unsaturated compoundconversion of greater than about 50%.
 8. A hydroformylation processwhich comprises reacting one or more olefinic unsaturated compounds withcarbon monoxide and hydrogen in the presence of ametal-organopolyphosphite ligand complex catalyst and optionally freeorganopolyphosphite ligand to produce a reaction product fluidcomprising one or more aldehydes, and in which said reaction productfluid contains at least some organomonophosphite ligand formed duringsaid hydroformylation process, wherein said hydroformylation process isconducted at a carbon monoxide partial pressure sufficient to preventand/or lessen coordination of the organomonophosphite ligand with saidmetal-organopolyphosphite ligand complex catalyst.
 9. The process ofclaim 1 which comprises a hydroformylation, hydroacylation(intramolecular and intermolecular), hydrocyanation, hydroamidation,hydroesterification, aminolysis, alcoholysis, carbonylation,isomerization or transfer hydrogenation process.
 10. The process ofclaim 6 in which the organomonophosphite ligand is treated with water, aweakly acidic compound, or both water and a weakly acidic compound. 11.The process of claim 10 wherein the organomonophosphite ligand ishydrolyzed to a phosphorus acidic compound comprising a hydroxy alkylphosphonic acid.
 12. The process of claim 4 wherein the temperaturedifference between reaction product fluid temperature and inlet coolanttemperature is less than about 20° C., the carbon monoxide conversion isless than about 75%, the hydrogen conversion is greater than about 85%,and the olefinic unsaturated compound conversion is greater than about50%.
 13. The process of claim 6 wherein the organomonophosphite ligandhas (a) a coordination strength with respect to the metal of saidmetal-organopolyphosphite ligand complex catalyst less than carbonmonoxide and (b) a coordination strength with respect to the metal ofsaid metal-organopolyphosphite ligand complex catalyst less than theorganopolyphosphite ligand of said metal-organopolyphosphite ligandcomplex catalyst.
 14. The process of claim 2 wherein said reactionproduct fluid contains a homogeneous or heterogeneousmetal-organopolyphosphite ligand complex catalyst or at least a portionof said reaction product fluid contacts a fixed heterogeneousmetal-organopolyphosphite ligand complex catalyst during saidhydroformylation process.
 15. The process of claim 1 wherein saidmetal-organopolyphosphite ligand complex catalyst comprises rhodiumcomplexed with an organopolyphosphite ligand represented by the formula:##STR6## wherein X represents a substituted or unsubstituted n-valentorganic bridging radical containing from 2 to 40 carbon atoms, each R¹is the same or different and represents a divalent organic radicalcontaining from 4 to 40 carbon atoms, each R² is the same or differentand represents a substituted or unsubstituted monovalent hydrocarbonradical containing from 1 to 24 carbon atoms, wherein a and b can be thesame or different and each have a value of 0 to 6, with the proviso thatthe sum of a+b is 2 to 6 and n equals a+b.
 16. The process of claim 11wherein phosphorus acidic compound present in the reaction product fluidof the hydroformylation process is treated with an aqueous buffersolution.
 17. The process of claim 16 wherein the aqueous buffersolution comprises a mixture of salts of oxyacids having a pH of 4 to 9.18. The process of claim 16 wherein phosphorus acidic compound presentin the reaction product fluid is scavenged by an organic nitrogencompound that is also present in said reaction product fluid and whereinat least some amount of the phosphorus acidic compound of the conversionproducts of the reaction between said phosphorus acidic compound andsaid organic nitrogen compound are also neutralized and removed by theaqueous buffer solution treatment.
 19. The process of claim 18 whereinthe organic nitrogen compound is selected from the group consisting ofdiazoles, triazoles, diazines and triazines.
 20. The process of claim 19wherein the organic nitrogen compound is benzimidazole or benzotriazole.